Abstract
Fibroin and sericin extracted from the lumen of the middle division of silkgland in the two mutants, naked pupa (Nd) and sericin-cocoon (Nd-s), were examined on polyacrylamide gel electrophoresis containing 8M urea, and the existence of different components in fibroin and sericin was demonstrated with the reduction of disulphide bonds. Proteins from the larval silkgland of the two mutants contained a small quantity of a fibroin fraction migrating with slower mobility than the light fraction of fibroin from a normal gland. The silkgland of Nd-s mutant contained a large quantity of a rapidly migrating component of sericin which is absent in the secretion from normal glands. However, the sericin extracted from Nd-gland consisted of the similar fractions as obtained from the normal gland.
