RBCC Red Blood Cell Collection

CO4B_HUMAN

Source: hRBCD ; ID: IPI00418163
PM19886704
PM23856902
BGMUT ; ID: chrg
BSc_CH
Marked as 'Non-membrane protein'
Confidence: high (a blood group or CD marker) Search PubMed for
(RBC AND this entry)
Gene names: C4B , CO4, CPAMD3
Protein names and data: CO4B_HUMAN , Complement C4-B , Basic complement C4; C3 and PZP-like alpha-2-macroglobulin domain-containing protein 3; Complement C4 beta chain; Complement C4-B alpha chain; C4a anaphylatoxin; C4b-B; C4d-B; Complement C4 gamma chain; Flags: Precursor Lenght: 1744 a.a.
Mass: 192751 Da
fasta formatted sequence
Function: Non-enzymatic component of the C3 and C5 convertases and thus essential for the propagation of the classical complement pathway. Covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and the clearance of IC through CR1 on erythrocytes. C4A isotype is responsible for effective binding to form amide bonds with immune aggregates or protein antigens, while C4B isotype catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens. Derived from proteolytic degradation of complement C4, C4a anaphylatoxin is a mediator of local inflammatory process. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes.
Disease: ( OMIM: 120820 152700 614374 614379 ) Systemic lupus erythematosus (SLE) [MIM:152700]: A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow. Note=Disease susceptibility is associated with variations affecting the gene represented in this entry. Interindividual copy-number variation (CNV) of complement component C4 and associated polymorphisms result in different susceptibilities to SLE. The risk of SLE susceptibility has been shown to be significantly increased among subjects with only two copies of total C4. A high copy number is a protective factor against SLE. Complement component 4B deficiency (C4BD) [MIM:614379]: A rare defect of the complement classical pathway associated with the development of autoimmune disorders, mainly systemic lupus with or without associated glomerulonephritis. Note=The disease is caused by mutations affecting the gene represented in this entry.
Cellular location: Secreted.
Tissue specificity: Complement component C4 is expressed at highest levels in the liver, at moderate levels in the adrenal cortex, adrenal medulla, thyroid gland,and the kidney, and at lowest levels in the heart, ovary, small intestine, thymus, pancreas and spleen. The extra-hepatic sites of expression may be important for the local protection and inflammatory response.

Genetic variants

The complement component C4 is the most polymorphic protein of the complement system. It is the product of 2 closely linked and highly homologous genes, C4A and C4B. Once polymorphic variation is discounted, the 2 isotypes differ by only 4 amino acids at positions 1120-1125: PCPVLD for C4A and LSPVIH for C4B. The 2 isotypes bear several antigenic determinants defining Chido/Rodgers blood group system [MIM:614374]. Rodgers determinants are generally associated with C4A allotypes, and Chido with C4B. Variations at these loci involve not only nucleotide polymorphisms, but also gene number and gene size. The second copy of C4B gene present in some individuals has been called C4B_2 by the HUGO Gene Nomenclature Committee (HGNC). Some individuals may lack either C4A, or C4B gene. Partial deficiency of C4A or C4B is the most commonly inherited immune deficiency known in humans with a combined frequency over 31% in the normal Caucasian population (PubMed:11367523).

347 - 347 S -> Y (in allotype C4B-long; dbSNP:rs139889867). VAR_023729 139889867
478 - 478 P -> L (in allotype C4B1-hi). VAR_069160
907 - 907 T -> A (in allotype C4B-long and allotype C4B2). VAR_023730
1073 - 1073 G -> D (in allotype C4B2 and allotype C4B5-Rg1). VAR_023731
1176 - 1176 S -> N (in allotype C4B1a; dbSNP:rs2746414). VAR_023732 2746414
1207 - 1207 A -> V (in allotype C4B5-Rg1; dbSNP:rs200888163). VAR_023734 200888163
1210 - 1210 R -> L (in allotype C4B5-Rg1; dbSNP:rs112683215). VAR_023735 112683215
1317 - 1317 I -> F (in allotype C4B1-SC01). VAR_069161

Database cross-references

UniProt: P0C0L5
Ensembl: ENST00000375177
Ensembl: ENST00000411583
Ensembl: ENST00000435363
Ensembl: ENST00000435500
Ensembl: ENST00000449788
MIM: 120820
MIM: 152700
MIM: 614374
MIM: 614379
neXtProt: NX_P0C0L5
Antibodypedia: P0C0L5 (may not find the protein thus also not any antibody)
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