An inverse relationship between receptor internalization and the fraction of laterally mobile receptors for the vasopressin renal-type V2-receptor. An active role for receptor immobilization in down-regulation?
Lateral mobility of the vasopressin renal-type V2-receptor was investigated in LLC-PK1 porcine epithelial cells using the technique of fluorescence microphotolysis (photobleaching) and a rhodamine-labelled vasopressin analogue. At various times after ligand addition, cells were analyzed for both receptor lateral mobility and ligand internalization. The V2-receptor mobile fraction diminished from 0.9 to 0.43 over 60 min at 37 degrees C, whereas the apparent lateral diffusion coefficient remained essentially unchanged (2-3 X 10(-10) cm2/s). Interestingly, the fraction of immobile V2-receptors corresponded exactly with the fraction of internalized receptors, implying a functional relationship. These observations together with comparable results reported for other polypeptide hormone receptors indicate a possible mechanistic role for receptor immobilization in the desensitization of hormonal response.
Jans
D A
DA
Max-Planck-Institut für Biophysik, Frankfurt/Main, FRG.
Peters
R
R
Fahrenholz
F
F
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D015536:Down-Regulation; D007668:Kidney; D007700:Kinetics; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin; D013552:Swine
D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin