Hormonal modulation of secretion of immunoreactive riboflavin carrier protein by adult rat Leydig cells in vitro.
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.
Subramanian
S
S
Department of Biochemistry, Indian Institute of Science, Bangalore, India.
Adiga
P R
PR
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
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