Characterization of insulin receptors in isolated epithelial cells of rat ventral prostate: effect of fasting.
Insulin receptors have been characterized in rat prostatic epithelial cells by using [125I]insulin and a variety of physicochemical conditions. The binding data at equilibrium (2 h at 15 degrees C) could be interpreted in terms of two populations of insulin receptors: a class of receptors with high affinity (Kd = 2.16 nM) and low binding capacity (28.0 fmol mg-1 protein), and another class of receptors with low affinity (Kd = 0.29 microM) and high binding capacity (1.43 pmol mg-1 protein). Proinsulin exhibited a 63-fold lower affinity than insulin for binding sites whereas unrelated peptides were ineffective. The specific binding of insulin increased by about 50 per cent after 96 h of fasting; this increase could be explained by an increase of both the number of the high affinity-low capacity sites and the affinity of the low affinity-high capacity sites. These results together with previous studies on insulin action at the prostatic level strongly suggest that insulin may exert a physiological role on the prostatic epithelium.
D000818:Animals; D001667:Binding, Competitive; D004848:Epithelium / Q000378:metabolism; D005215:Fasting; D066298:In Vitro Techniques; D007328:Insulin / Q000031:analogs & derivatives / Q000378:metabolism; D007700:Kinetics; D008297:Male; D011467:Prostate / Q000378:metabolism*; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*
D007328:Insulin; C008147:insulin, iodo-; D011972:Receptor, Insulin