title: Hormonal modulation of secretion of immunoreactive riboflavin carrier protein by adult rat Leydig cells in vitro.
abstract: Adult rat Leydig cells in culture synthesize and secrete riboflavin carrier protein (RCP) as demonstrated by [35S]-methionine incorporation into newly synthesized proteins followed by immunoprecipitation as well as specific radioimmunoassay. LH stimulates the secretion of RCP 4-fold which could be inhibited upto 75% by an aromatase inhibitor. 8-bromo-cyclic AMP and cholera toxin could mimic the LH stimulated secretion of the carrier protein. The extent of stimulation of RCP secretion brought about by exogenous estradiol-17 beta is comparable to that of LH. The antiestrogen tamoxifen, when added along with either LH or estrogen, inhibited the stimulated levels significantly. These results show that the estrogen-inducible riboflavin carrier is secreted by Leydig cells under positive regulation of LH.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore, India.
authors.forename: S
authors.initials: S
authors.lastname: Subramanian
authors.forename: P R
authors.initials: PR
authors.lastname: Adiga
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D008297:Male; D026901:Membrane Transport Proteins; D051381:Rats; D017208:Rats, Wistar; D012256:Riboflavin / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D004965:Estrogen Antagonists; D026901:Membrane Transport Proteins; C019079:riboflavin-binding protein; D013629:Tamoxifen; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004958:Estradiol; D007986:Luteinizing Hormone; D012256:Riboflavin