MOLECULAR-CLONING OF FROG SECRETOGRANIN-II REVEALS THE OCCURRENCE OF SEVERAL HIGHLY CONSERVED POTENTIAL REGULATORY PEPTIDES

Secretogranin II (SgII) is an acidic secretory protein present in larg e dense core vesicles of neuronal and endocrine cells, Based on the se quence of a peptide derived from the processing of SgII in the brain o f the frog Rana ridibunda, degenerate oligonucleotides were used to cl one the cDNA encoding frog SgII from a pituitary cDNA Library. This cD NA encodes a 574 amino acid protein which exhibits 46-48% sequence ide ntity with mammalian SgII and contains 11 pairs of basic amino acids, Four potential processing products delimited by pairs of basic residue s exhibited a much higher degree of identity (68-82%) with the corresp onding mammalian SgII sequences, The frog SgII mRNA is similar to 4 kb in length and is differentially expressed in the brain and endocrine tissues, The present data reveal that several SgII-derived peptides ha ve been highly conserved during evolution, suggesting that these pepti des may play important neuroendocrine regulatory functions.