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A relaxin‐like gonad‐stimulating peptide identified from the starfish Astropecten scoparius
Author(s) -
Mita Masatoshi,
Osugi Tomohiro,
Matsubara Shin,
Kawada Tsuyoshi,
Satake Honoo,
Katayama Hidekazu
Publication year - 2021
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.23444
Subject(s) - biology , peptide , biochemistry , gamete , peptide sequence , relaxin , starfish , signal peptide , sperm , receptor , genetics , gene , ecology
A relaxin‐like gonad‐stimulating peptide (RGP) in starfish was the first identified invertebrate gonadotropin responsible for final gamete maturation. An RGP ortholog was newly identified from Astropecten scoparius of the order Paxillosida. The A. scoparius RGP (AscRGP) precursor is encoded by a 354 base pair open reading frame and is a 118 amino acid (aa) protein consisting of a signal peptide (26 aa), B‐chain (21 aa), C‐peptide (47 aa), and A‐chain (24 aa). There are three putative processing sites (Lys‐Arg) between the B‐chain and C‐peptide, between the C‐peptide and A‐chain, and within the C‐peptide. This structural organization revealed that the mature AscRGP is composed of A‐ and B‐chains with two interchain disulfide bonds and one intrachain disulfide bond. The C‐terminal residues of the B‐chain are Gln‐Gly‐Arg, which is a potential substrate for formation of an amidated C‐terminal Gln residue. Non‐amidated (AscRGP‐GR) and amidated (AscRGP‐NH 2 ) peptides were chemically synthesized and their effect on gamete shedding activity was examined using A. scoparius ovaries. Both AscRGP‐GR and AscRGP‐NH 2 induced oocyte maturation and ovulation in similar dose‐dependent manners. This is the first report on a C‐terminally amidated functional RGP. Collectively, these results suggest that AscRGP‐GR and AscRGP‐NH 2 act as a natural gonadotropic hormone in A. scoparius .