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REG protein was shown to be stimulated during the regeneration of pancreatic islets. Since then, many Reg-related proteins have been identified in humans and other animals. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. These Reg-related proteins are classified into four subfamilies according to their amino-acid sequences, but they share a similar structure and physiological function. Reg protein is a growth factor for pancreatic beta cells and also suggests that the administration of Reg protein could be used as another therapeutic approach for diabetes mellitus. Human REG cDNA which encodes a 166-amino acid protein with a 22-amino acid signal peptide. The amino acid sequence of human REG protein has 68% homology to that of rat Reg protein.
Reg I was found to be expressed mainly in pancreatic beta and acinoductular cells as well as gastric fundic enterochromaffin-like (ECL) cells. Reg I production in ECL cells is stimulated by gastrin, as well as by the proinflammatory cytokine, cytokine-induced neutrophil chemoattractant (CINC)-2Beta. In patients with chronic hypergastrinemia, Reg production is stimulated, with the increased proliferation of gastric mucosal cells. Patients with Helicobacter pylori infection also showed increased Reg production in the gastric mucosa, partly via increased plasma gastrin concentration and partly via increased proinflammatory cytokine production. The serum concentration of the reg-protein was significantly higher in patients with various pancreatic diseases than in normal controls, and was also significantly higher in patients with acute pancreatitis or chronic relapsing pancreatitis than in patients with chronic pancreatitis. Furthermore, the serum PSP/reg-protein concentration was also significantly increased in liver cirrhosis, choledocholithiasis, and various cancers of the digestive system.

Tachykinin-1 (TAC1) belongs to the tachykinin peptide hormone family. TAC1 are a family of peptides which have similar biologic activities and share a common C-terminal sequence, phe-X-gly-leu-met-NH2, however they have distinct N-terminal sequences that convey receptor specificities. TAC1 is assumed to act as neurotransmitters which interact with nerve receptors and smooth muscle cells. TAC1 induces behavioral responses and serves as vasodilators and secretagogues.

CALR is a multifunctional protein that acts as a main Ca(2+)-binding (storage) protein in the lumen of the endoplasmic reticulum. Calreticulin is localized in the nucleus, and participates in transcription regulation. Calreticulin binds to the synthetic peptide KLGFFKR, which is nearly identical to an amino acid sequence in the DNA-binding domain of the superfamily of nuclear receptors. CALR binds to antibodies in specific sera of systemic lupus and Sjogren patients which have anti-Ro/SSA antibodies, it is well conserved among species, and it is positioned in the endoplasmic and sarcoplasmic reticulum where it binds calcium. The amino terminus of CALR interacts with the DNA-binding domain of the glucocorticoid receptor and prevents the receptor from binding to its specific glucocorticoid response element. CALR reduces the binding of androgen receptor to its hormone-responsive DNA element and inhibits androgen receptor and retinoic acid receptor transcriptional activities in vivo, as well as retinoic acid-induced neuronal differentiation. Therefore, CALR acts as a significant modulator of the regulation of gene transcription by nuclear hormone receptors.

CASQ2 belongs to the calsequestrin family and is localized to the sarcoplasmic reticulum in cardiac and slow skeletal muscle cells. CASQ2 is a calcium binding protein that stores calcium for muscle function. The discharge of calcium bound to CASQ2 through a calcium release channel activates muscle contraction. CASQ2 binds 40 to 50 moles of calcium. CASQ2 mutations result in stress-induced polymorphic ventricular tachycardia, also called catecholaminergic polymorphic ventricular tachycardia 2 which is known fir its bidirectional ventricular tachycardia that causes cardiac arrest.

CASQ2 belongs to the calsequestrin family and is localized to the sarcoplasmic reticulum in cardiac and slow skeletal muscle cells. CASQ2 is a calcium binding protein that stores calcium for muscle function. The discharge of calcium bound to CASQ2 through a calcium release channel activates muscle contraction. CASQ2 binds 40 to 50 moles of calcium. CASQ2 mutations result in stress-induced polymorphic ventricular tachycardia, also called catecholaminergic polymorphic ventricular tachycardia 2 which is known fir its bidirectional ventricular tachycardia that causes cardiac arrest.

Regulation Of Nuclear Pre-MRNA Domain Containing 1A (RPRD1A) is upregulated in cells overexpressing cyclin-dependent kinase inhibitor p15(INK4b) and may have a part in cell cycle regulation. RPRD1A interacts with phosphorylated C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit POLR2A, and partakes in dephosphorylation of the CTD. RPRD1A May function as a negative regulator of cyclin-D1 (CCND1) and cyclin-E (CCNE1) in the cell cycle.

CACYBP (calcyclin binding protein) participates in calcium-dependent ubiquitination and subsequent proteosomal degradation of target proteins. CACYBP acts as a molecular bridge in ubiquitin E3 complexes. CACYBP is involved in the ubiquitin-mediated degradation of beta-catenin.

S100A9 is part of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100A9 protein is localized in the cytoplasm and/or nucleus of a wide range of cells, and participates in the regulation of several cellular processes such as cell cycle progression and differentiation. S100 genes include no less than 13 proteins which are localized as a cluster on chromosome 1q21. S100A9 is involved in the inhibition of casein kinase and altered expression of this protein is associated with the disease cystic fibrosis.

GNLY is part of the SAPLIP family and is located in the cytotoxic granules of T cells, which are discharged upon antigen stimulation. GNLY is localized in cytotoxic granules of cytotoxic T lymphocytes and natural killer cells, and it has antimicrobial activity against M. tuberculosis and other organisms. GNLY is an antimicrobial protein that kills intracellular pathogens. GNLY is active against a wide range of microbes, including Gram-positive and Gram-negative bacteria, fungi, and parasites. Kills Mycobacterium tuberculosis.

MED7 is a member of the Mediator complex subunit 7 family. The activation of gene transcription is a multistep course which is initiated by factors which identify transcriptional enhancer sites in DNA and collaborate with co-activators to direct transcriptional initiation by the RNA polymerase II apparatus. The gene encode a subunit of the CRSP (cofactor required for SP1 activation) complex, that, together with TFIID, is needed for effective activation by SP1. Additionally, MED7 is also an element of other multisubunit complexes e.g. thyroid hormone receptor-(TR-) associated proteins that cooperate with TR and enables TR function on DNA templates in conjunction with initiation factors and cofactors.

Canopy FGF Signaling Regulator 1, also known as CNPY1, is expressed in the midbrain-hindbrain (MHB) boundary in zebrafish. CNPY1, which binds FGFR1, also takes part in FGF signaling.

Calbindins are Ca-binding proteins belonging to the troponin C superfamily. CALB28K/Calbindin1/CALB1 (D28K/Spot35 protein or cholecalcin, rat 261 aa; mouse 261 aa; human 261-aa, chromosome 8q21.3-q22.1) was originally described as 27-kDA induced by vitamin D in the duodenum of chicken. In mammals, it is expressed in the kidney, pancreatic islets, and brain. In brain, its synthesis is independent of vitamin D. CABP28K contains 4 active and 2 inactive EF-hand Ca-binding domains. The gene for CABP28K is clustered in the same region as carbonic anhydrase. The neurons in the brains of patients with Huntington disease are CAB28K depleted. There are two types of CaBPs: the "trigger"- and the "buffer"-CaBPs. The conformation of "trigger" type CaBPs changes upon Ca2+ binding and exposes regions on protein that interact with target molecules, thus altering their activity. The buffer-type CABP are thought to control the intracellular calcium concentration. Calbindin D-28K is found predominantly in subpopulations of central and peripheral nervous system neurons, and in certain epithelial cells involved in Ca2+ transport such as distal tubular cells and cortical collecting tubules of the kidney, and in enteric neuroendocrine cells.

Calmodulin Like 5, also known as CALML5 is a part of the calmodulin family of calcium binding proteins. CALML5 undergoes a conformational change as a result of binding calcium. CALML5 is taking part in terminal differentiation of keratinocytes and encodes a calcium binding protein expressed in the epidermis.

Calumenin is a calcium-binding protein located in the endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) of mammalian tissues which plays a role in ER functions as protein folding and sorting. Calumenin belongs to a family of multiple EF-hand proteins (CERC) that include reticulocalbin, ERC-55, and Cab45 and the product of this gene. Calumenin binds 7 calcium ions having low affinity and takes part in such ER functions as protein folding and sorting.

Calreticulin 3 (CALR3) belongs to the calreticulin (CRT) family which consists of calcium binding chaperones that are localized to the endoplasmic reticulum or sarcoplasmic reticulum in eukaryotes. CALR3, which is expressed mainly in testis, takes part in protein-folding, oligomeric assembly and quality control in the ER. CALR3 plays an important role as a cancer-testis antigen due to its frequent expression in many cancers.

RERG is a 199 amino acid protein which localizes in the cytoplasm and is a member of the Ras subfamily of small GTPases. RERG is expressed in the pancreas, liver, skin, lung, brain, kidney and heart tissue. RERG is a vital mediator of diverse cell signaling pathways, including those leading to cell proliferation, cytoskeletal organization and secretion.

Calbindin 1 (CALB1) is a calcium binding protein that is a member of the troponin C superfamily. CALB1 plays a vital role in calcium regulation (including calcium transport and uptake, calcification of bone and teeth) and calcium associated signaling in neurons and transiently in embryological development. CALB1 also has a role in protecting neurons from apoptotic cell death. CALB1 buffers cytosolic calcium and may stimulate a membrane Ca2+-ATPase and a 3',5'-cyclic nucleotide phosphodiesterase. The biological function of CALB1 seems to be tied to the redox state of its five cysteine residues.
CALB1 has 4 active calcium-binding domains, and 2 modified domains that seemingly have lost their calcium-binding ability. CALB1 is expressed in neural tissues. In the brain, the CALB1 synthesis is independent of vitamin-D-derived hormones.
Disregulation of the CALB1 is associated with epilepsy, amyotrophic lateral sclerosis, Huntington's disease. The neurons in brains of Huntington disease patients are calbindin-depleted.

Pancreatitis-associated protein (PAP) is a secretory protein not normally expressed in healthy pancreas but highly induced during acute pancreatitis. While PAP has been shown to be anti-bacterial and antiapoptotic in vitro, its definitive biological function in vivo is not clear. Using antisepse oligonucleotides, inhibition of PAP expression significantly worsened pancreatitis in a rat model. During pancreatitis, PAP released by the pancreas could mediate lung inflammation through induction of hepatic TNF- alpha expression and subsequent increase in circulating TNF-alpha.
PAP is activated in primary liver cancers. In normal liver, the protein is undetectable in normal mature hepatocytes and found only in some ductular cells, representing potential hepatic progenitor cells. PAP can be considered hepatic cytokine that combines mitogenic and anti-apoptotic functions regarding hepatocytes, and consequently acts as a growth factor in vivo to enhance liver regeneration. In pancreatic cancor, PAP was overexpressed in 79% (30 of 38) of pancreatic ductal adenocarcinoma, 19% (7 of 36) of chronic pancreatitis, and 29% (2 of 7) of mucinous cystadenoma. PAP was found in malignant ductular structures in pancreatic carcinomas as well as in benign proliferating ductules and acinar cells in chronic pancreatitis. Elevation of PAP in patients with pancreatic cancer is not merely explainable by concomitant pancreatitis, but seems to be due to increased PAP production by the cancer cells and is also correlated to tumour load as expressed by the UICC stages.
Epithelial expression of PAP was induced under intestinal mucosal inflammation initiated by exposure to commensal bacteria or DSS as well as inflamed IBD colon. Increased serum level of PAP diagnosed ileal location in active Crohn disease with a sensitivity of 60%, a specificity of 94%, a positive predictive value of 84% and a negative predictive value of 81%. Elevated serum PAP (> 50 ng/mL) is significantly associated with disease activity and ileal location of Crohn disease.

DR1 is a phosphoprotein that inhibits both basal and activated levels of transcription. DR1 is phosphorylated in vivo which affects its interaction with TBP. DR1 has a histone fold motif at the amino terminus, a TBP-binding domain, and a glutamine- and alanine-rich region. By selectively repressing polymerases II and III, DR1 alters the physiological balance of transcriptional output in favor of polymerase I.

CAPSL is a calcium-binding protein holding two conserved calcium-binding motifs (EF-hands) which are found in a superfamily of calcium sensors and calcium signal modulators. In addition, the CAPSL gene is in the same linkage disequilibrium (LD) block as the IL7R gene and there is well known association between the CAPSL-IL7R locus and type 1 diabetes.

Alpha 1-microglobulin (A1M) is a lipocalin superfamily member (kernal lipocalins). A1M is a low molecular weight protein component of plasma. A1M is distributed in plasma and extravascular compartments of all organs. Alpha-1 Microglobulin is found in mammals, birds, amphibians and fish. The primary sites of A1M synthesis are the liver and the kidney. Around the opening of the lipocalin pocket three lysyl residues are situated; those residues carry yellow-brown modification derived from the binding and degradation of heme and kynurenin (a tryptophan metabolite). A1-Microglobulin’s reductase and dehydrogenase have broad biological substrate specificity properties due to its’ free cysteine side-chain which is located in a flexible loop. Alpha-1-microglobulin is glycosylated by three separate carbohydrate chains: two complex carbohydrates which are N-linked to asparagines at residues 17 and 96, and the other simple carbohydrate which is O-linked to threonine at position 5. The carbohydrates comprise 22% of the total molecular mass of the protein. The glycosylation varies between species.
A1M exists in two forms- a free form and complexed to other macromolecules: in humans- complexed to immunoglobulin A (IgA), in rat- complexed to alpha-1-inhibitor-3. Free A1M is exceptionally heterogeneous in charge (therefore also known as protein HC), and is found tightly linked to a chromophore. The free Alpha-1-microglobulin is a monomeric protein composed of one 188 residue polypeptide and contains three cysteines, two of which (residues 75 and 173) form a conserved intra-molecular disulphide link. The chromophoric group is covalently bound to the free cysteine residue at position 34. A1M binds retinol as a major ligand, but this is probably distinct from its covalent chromophore.
Half of all human plasma A1M (approximately 0.03mg/ml) forms a 1:1 complex with about 5% of plasma immunoglobulin A. The resulting macromolecular complexes’ molecular weight is 200000, and a plasma concentration of 0.3mg/ml. The complex can exhibit both antibody activity and affect many of the biological actions of free Alpha-1-microglobulin.
Alpha-1-microglobulin was first discovered in pathological human urine.
It was suggested that A1M might be involved in tissue defense against reactive oxygen species, oxidation by heme and kynurenin. Evidence also suggests that A1M functions in the regulation of the immune system. Other functions include inhibition of stimulation of cultured lymphocytes by protein antigens; induction of cell division of lymphocytes, a mitogenic effect that can either be enhanced or inhibited by the action of other plasma components; inhibition of neutrophil granulocyte migration in vitro; and inhibition of chemotaxis.

The somatomedins, or insulin-like growth factors (IGFs), comprise a family of peptides that play important roles in mammalian growth and development. IGF1 mediates many of the growth-promoting effects of growth hormone (GH; MIM 139250). Early studies showed that growth hormone did not directly stimulate the incorporation of sulfate into cartilage, but rather acted through a serum factor, termed 'sulfation factor,' which later became known as 'somatomedin' (Daughaday et al., 1972). Three main somatomedins have been characterized: somatomedin C (IGF1), somatomedin A (IGF2; MIM 147470), and somatomedin B (MIM 193190) (Rotwein, 1986; Rosenfeld, 2003).