Cloning and sequence analysis of cDNAs encoding two distinct somatostatin precursors found in the endocrine pancreas of anglerfish

Abstract

Complementary DNA for 2 distinct anglerfish [L. americanus] somatostatin peptides (termed I and II) were cloned in bacterial plasmids and sequenced. The nucleotide sequence for somatostatin I encodes a large precursor peptide (MW 13,300) in which the somatostatin hormone is at the carboxyl terminus. The predicted 14 amino acid sequence for anglerfish somatostatin I is the same as for mammalian somatostatin. Somatostatin II is also synthesized as part of a larger precursor (MW 14,100) with the presumptive somatostatin hormone also at the carboxyl terminus. The 14 amino acid sequence of somatostatin II differs from somatostatin I at 2 internal residues (Tyr in place of Phe 7 and Gly in place of Thr 10). The 2 different somatostatins may have distinct biological activities. Homologies in the amino acid sequences of the 2 peptides outside the somatostatin moiety suggest that other regions of the molecules have biological functions.