High sulfur proteins are cysteine-rich proteins synthesised during the differentiation of hair matrix cells, and form hair fibres in association with hair keratin intermediate filaments [1]. This family has been divided up into four regions, with the second region containing 8 copies of a short repeat [1]. This family is also known as B2 or KAP1.

1: Structure and hair follicle-specific expression of genes encoding the rat high sulfur protein B2 family. Mitsui S, Ohuchi A, Adachi-Yamada T, Hotta M, Tsuboi R, Ogawa H; Gene 1998;208:123-129. PMID:9524245