CHARACTERIZATION OF A GENE ENCODING A CYSTEINE-RICH KERATIN ASSOCIATED PROTEIN SYNTHESIZED LATE IN RABBIT HAIR FOLLICLE DIFFERENTIATION

Many different cysteine-rich proteins are synthesized during hair foll icle differentiation, forming part of the interstitial matrix between bundles of intermediate filaments. We have isolated a rabbit gene (rKA P4L(1)), a member of a multigene family that encodes a small cysteine- rich hair keratin associated protein. This is the first complete gene sequence for this family. The rKAP4L gene is expressed in the cortex o f rabbit pelage hair follicles at a late stage of hair follicle differ entiation, well after the synthesis of the other major hair proteins, the intermediate filament and glycine/tyrosine-rich keratin associated proteins, has commenced. The protein contains 36 mol % cysteine, with a molecular size of 13593 daltons, and its sequence appears to be bas ed on a pentapeptide repeat. It is predicted to adopt a folded conform ation characterized by beta-turns interspersed with short stretches of beta-sheet or random coil.