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

David A. Jans, Reiner Peters, Falk Fahrenholz

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Abstract

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°C was 5.1 × 10-10cm2/s, falling to 2.9 × 10-10 cm2/s at 13°C. These D values are higher than comparable values for the adenylate cyclaseactivating 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°C to 13°C, f was relatively low (between 0.4 and 0.5) consistent with V1receptor 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.

Original languageEnglish
Pages (from-to)2693-2699
Number of pages7
JournalThe EMBO Journal
Volume9
Issue number9
Publication statusPublished - 1 Dec 1990
Externally publishedYes

Keywords

  • Lateral mobility
  • Photobleaching
  • Smooth muscle cell line
  • Vasopressin V-receptor

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