Locations of synthesis of hair structural proteins in human anagen follicles.

Live tissue containing cells of the presumptive hair shaft (PHS), was obtained by microdissection of human anagen hair follicles. Whole PHS, as well as PHS further dissected into three levels of hair development, were subsequently used in protein solubilization procedures. Single- and two-dimensional polyacrylamide gel electrophoresis (PAGE) of radiolabelled extracts, with fluorography, enabled comparison of hair and PHS keratin proteins. Fluorographs demonstrated the major classes of protein comprising the intermediate filaments (IF) and matrix of hair keratins. In addition, extracts from various levels of PHS tissue have provided direct evidence for the locations of synthesis of these protein moieties. Thus, IF and matrix proteins are synthesized sequentially in PHS. A previously unobserved polypeptide component, not present in hair extracts, has been identified and found to vary in relative proportions when compared with the major IF and matrix protein classes as PHS cells differentiate to form hair. In the absence of reliable methods for extraction of human hair, PHS provides an alternative source of material, despite the extra burden of follicle collection and specimen preparation. The procedures described provide a new basis for studying human hair defects and are potentially useful for comparing human hair proteins in a variety of situations.