Tbio C4B Complement C4-B

Protein Summary

Description

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. This gene encodes the basic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. [provided by RefSeq, Jul 2008]

Uniprot Accession IDs

• P0C0L5
• A2BHY4
• P01028
• P78445
• Q13160
• Q13906
• Q14033
• Q14835
• Q6U2E9
• Q6U2G1
• Q6U2I5
• Q6U2L1
• Q6U2L7
• Q6U2L9
• Q6U2M5
• Q6VCV8
• Q96SA7
• Q9NPK5
• Q9UIP5

Gene Name

• C4B

Ensembl ID

• ENST00000375177
• ENSP00000364321
• ENSG00000228454
• ENST00000411583
• ENSP00000407942
• ENSG00000228267
• ENST00000435363
• ENSP00000415941
• ENSG00000224389
• ENST00000435500
• ENSP00000412786
• ENSG00000233312
• ENST00000449788
• ENSP00000414200
• ENSG00000236625

Symbol

• CO4
• CPAMD3
• CH
• C4F
• CO4
• C4B1
• C4B2
• C4B3
• C4B5
• C4BD
• C4B12
• C4B_2
• CPAMD3

Knowledge Table

Most Knowledge About	Knowledge Value (0 to 1 scale)
protein complex	1
biological term	0.82
small molecule perturbation	0.81
cell line	0.68
disease	0.67

Protein Classes

PANTHER Classes

Protein / Signaling Molecule / Cytokine / Complement C4-b

Protein / Enzyme Modulator / Protease Inhibitor / Serine Protease Inhibitor / Complement C4-b

Protein / Defense/immunity Protein / Complement Component / Complement C4-b

DTO Classes

Protein / Enzyme Modulator / Protease Inhibitor / Serine Protease Inhibitor / Complement C4-b

IDG Development Level Summary

Tdark

These are targets about which virtually nothing is known. They do not have known drug or small molecule activities
- AND - satisfy two or more of the following criteria:

Pubmed score: 1957.9   (req: < 5)

Gene RIFs: 131   (req: <= 3)

Antibodies: 296   (req: <= 50)

Tbio

These targets do not have known drug or small molecule activities
- AND - satisfy two or more of the following criteria:

Pubmed score: 1957.9   (req: >= 5)

Gene RIFs: 131   (req: > 3)

Antibodies: 296   (req: > 50)

- OR - satisfy the following criterion:

Gene Ontology Terms: 12

Tchem

Target has at least one ChEMBL compound with an activity cutoff of < 30 nM - AND - satisfies the preceding conditions

Active Ligand: 0

Tclin

Target has at least one approved drug - AND - satisfies the preceding conditions

Active Drug: 0