Lateral mobility of the phospholipase C-activating vasopressin V1-type receptor in A7r5 smooth muscle cells: a comparison with the adenylate cyclase-coupled V2-receptor.
The present work examines lateral mobility of the vasopressin V1-type receptor, representing the first determination of lateral mobility of a hormone receptor coupled to phospholipase C activation. The V1-receptor of A7r5 smooth muscle cells was characterized for [Arg8] vasopressin (AVP) binding properties and affinity for the fluorescent vasopressin analogue 1-deamino[8-lysine (N6-tetramethylrhodamylaminothiocarbonyl)] vasopressin (TR-LVP). TR-LVP was biologically active in A7r5 cells, inducing inositol 1,4,5-trisphosphate turnover in similar fashion to AVP. TR-LVP was used to specifically label the V1-receptor of living A7r5 cells, and lateral mobility of the V1-receptor was measured using the technique of fluorescence microphotolysis. The apparent lateral diffusion coefficient (D) at 37 degrees C was 5.1 x 10(-10) cm2/s, falling to 2.9 x 10(-10) cm2/s at 13 degrees C. These D values are higher than comparable values for the adenylate cyclase-activating vasopressin V2-receptor of LLC-PK1 renal epithelial cells analysed with the same fluorescent ligand. In contrast to the V2-receptor, no marked temperature dependence was observed for the V1-receptor mobile fraction (f). From 37 degrees C to 13 degrees C, f was relatively low (between 0.4 and 0.5) consistent with V1-receptor immobilization through internalization, which is rapid even at room temperature in A7r5 cells. These differences between V1- and V2-receptor lateral mobility are discussed in terms of the implications for their respective signal transduction systems.
Jans
D A
DA
Max-Planck-Institut für Biophsik, Frankfurt am Main, FRG.
Peters
R
R
Fahrenholz
F
F
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D007700:Kinetics; D009130:Muscle, Smooth; D011945:Receptors, Angiotensin / Q000378:metabolism*; D017483:Receptors, Vasopressin; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D010738:Type C Phospholipases / Q000378:metabolism*
D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases