Search by BoMiProt ID - Bomi5

Primary Information

BoMiProt ID Bomi5
Protein Name Complement C4
Organism Bos taurus
Uniprot IdP01030
Milk FractionWhey
Amino Acid Lenth 920
Molecular Weight 101885
Fasta Sequence
Gene Name C4
Protein Existence Status Reviewed: Experimental evidence at protein level

Secondry Information

Protein Function most heterogeneous protein of the complement system; act as opsonizing molecules; C4b2a complex (the CP C3 convertase) remains on the activator and mediates downstream activation by cleaving C3 into C3b and C3a; C4b may offer a nucleophile for the cleavage of the thioester in nascent C3b
Biochemical Properties C4A is more prone to attach to amine groups of an activator, whereas C4B reacts preferentially with hydroxyl groups;
Significance in milk recruit inflammatory leucocytes to the sites of an inflammation and activate their effector mechanisms
PTMs Glycosylated: 4 N linked glycosylation site; α and ß-chains are glycosylated, but no accurate assessment of carbohydrate content in the γ-chain has been reported; C4 in human plasma contains mannose, galactose, glucosamine and sialic acid; contain complex biantennary glycans with varying degrees of sialylation; Human C4A recovered from cerebrospinal fluid was identified to contain an O-linked core 1 glycan; sulfation of three tyrosine residues
Additional Comments Carbohydrate incorporation can be blocked by tunicamycin; underglycosylated pro-C4 protein is more rapidly catabolized than the corresponding fully glycosylated protein; underglycosylated native C4, produced in the presence of tunicamycin, had approximately the same specific biological activity as glycosylated C4
Bibliography 1. Akita EM, Li-Chan ECY. Isolation of Bovine Immunoglobulin G Subclasses from Milk, Colostrum, and Whey Using Immobilized Egg Yolk Antibodies. J Dairy Sci. 1998;81(1):54–63.
2. Matthews WJ, Goldberger G, Marino JT, Einstein LP, Gash DJ, Colten HR. Complement proteins C2, C4 and factor B. Effect of glycosylation on their secretion and catabolism. Biochem J. 1982;204(3):839–46.
3. Zimmerman B, Kelly B, McMillan BJ, Seegar TCM, Dror RO, Kruse AC, et al. Crystal Structure of a Full-Length Human Tetraspanin Reveals a Cholesterol-Binding Pocket. Cell. 2016 Nov 3;167(4):1041-1051.e11.