The constituents of storage granules in the dermal glands of Xenopus laevis. Structure of a basic polypeptide deduced from cloned cDNA.

Mature dermal glands of Xenopus laevis contain storage granules with a characteristic ellipsoid shape. A few major proteins are present in these granules, including two with the same amino-terminal sequence and apparent molecular masses of 26 and 28 kDa. Using antibodies against these proteins, positive clones were isolated from a cDNA expression library prepared from skin of X. laevis. One cDNA encodes a preprotein with a typical signal sequence and a mature part of 187 amino acids. The protein shows internal homology at both the amino and carboxyl end. The latter part has a very high content of basic amino acids.