Da. Roess et al., LUTEINIZING-HORMONE RECEPTORS ARE ASSOCIATED WITH NONRECEPTOR PLASMA-MEMBRANE PROTEINS ON BOVINE LUTEAL CELL-MEMBRANES, Biochimica et biophysica acta. Biomembranes, 1371(1), 1998, pp. 5-10
Biophysical studies of the bovine luteinizing hormone (LH) receptor on
luteal cell membranes suggest that this receptor may be part of a lar
ger molecular weight structure. We have used 5-iodonaphthyl-1-azide (I
NA) to identify plasma membrane proteins near LH receptors on plasma m
embranes from bovine corpora lutea. Following binding of eosin isothio
cyanate-derivatized ovine LH or human chorionic gonadotropin (hCG), fi
ve proteins with molecular weights of 71, 57, 55, 49 and 36 kDa were s
electively derivatized with [I-125]-INA following 2 h exposure at 22 d
egrees C to 514 nm light. However, there was no fluorescence energy tr
ansfer between LH receptors occupied by ovine LH or hCG indicating tha
t LH receptors were not self-associated in these membrane preparations
. Together these results suggest that, following hormone binding, sing
le copies of the LH receptor may exist in large molecular weight struc
tures that include non-receptor proteins. (C) 1998 Elsevier Science B.
V.