Insulin B chain (Insulin B chain (30 amino acids))

The Insulin B chain is a 30-amino-acid polypeptide that forms one half of the mature insulin hormone, linked to the 21-amino-acid A chain by two interchain disulfide bonds (CysA7-CysB7 and CysA20-CysB19) and featuring structural elements like a central α-helix (residues B9-B19), β-turns, and a C-terminal β-strand. It arises from proteolytic processing of proinsulin in pancreatic β-cell granules, where prohormone convertases cleave the C-peptide, yielding active insulin that self-assembles into zinc-stabilized hexamers for storage and release. Upon secretion, hexamers dissociate to monomers that bind the insulin receptor, triggering tyrosine kinase activity, IRS phosphorylation, and downstream effects on glucose uptake (via GLUT4), glycolysis, lipogenesis, and inhibition of gluconeogenesis. The B chain's N-terminus adopts T- or R-state conformations critical for receptor binding and hexamer stability, with residues like GlyB8, B23-B26 enabling high-affinity interactions. In disease, B-chain peptides (e.g., B:9-23) serve as autoantigens in type 1 diabetes, recognized by CD4+ T cells, potentially forming hybrid peptides that enhance immunogenicity. It is not a standalone therapeutic target like receptors or enzymes but integral to insulin therapeutics for diabetes management.

Other names

B chain of insulinInsulin chain BChain B