Highly-expressed S100A3, a calcium-binding protein, in human hair cuticle

Analyses on sodium dodecyl sulfate-polyacrylamide gel electrophoreses showed that the human hair cuticle extracts mainly consist of a 7-kDa component and keratin proteins. The S-carboxymethylation of the cuticle extracts made the 7-kDa band shift to the 15-kDa position. After electroblotting of the S-carboxymethyl derivative, the membrane pieces carrying the 15-kDa band were treated with trypsin and the released peptides were separated by reverse-phased HPLC. Amino acid sequence analyses revealed that the peptides corresponded to the partial sequences deduced from human genome coding for S100A3, a cysteine-rich calcium binding protein. The anti S100A3 serum, prepared by immunizing a synthetic peptide antigen, reacted with the 7-kDa and 15-kDa bands in immunoblotting analyses. Immunofluorescence microscopy showed intense labeling to the cuticular layer with the anti S100A3 serum. These results indicated that S100A3 was highly expressed in the human hair cuticle.