Isolation of an egg-laying hormone-binding protein from the gonad of Aplysia californica and its localization in oocytes.
A protein solubilized from a membrane preparation of the gonad of Aplysia californica has been isolated by affinity chromatography, using bag cell egg-laying hormone (ELH) as the bound ligand, and partially purified and characterized by gel electrophoresis. The protein has an apparent molecular weight of 52 kDa and consists of two disulfide-linked subunits of about 30 kDa each. The protein is glycosylated and has an acidic pI. Approximately 10-15 micrograms of this protein can be isolated from a single ovotestis, representing less than 1% of the total protein in the gonad; but the protein could not be detected in buccal mass or body wall, tissues which do not have apparent response to ELH. Antibodies generated against this ELH-binding protein (ELHBP) were used to localize sites in the ovotestis which might contain this molecule and thus represent targets for egg-laying hormone. Immunocytochemical results indicate that the oocytes are a rich source of this protein, since their cytoplasm was the only detectable site of immunoreactivity. Whether this binding protein represents an egg-laying hormone receptor is uncertain, but its prevalence in oocytes suggests that ELH plays a signaling role on these gametes.
Choate
J V
JV
Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-0843.
Kruger
T E
TE
Micci
M A
MA
Blankenship
J E
JE
D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006066:Gonads / Q000737:chemistry*; D007150:Immunohistochemistry; D007447:Invertebrate Hormones / Q000302:isolation & purification*; D009865:Oocytes / Q000378:metabolism*
D007447:Invertebrate Hormones; C026880:egg-laying hormone, Mollusca