Two distinct calmodulin binding sites in the third intracellular loop and carboxyl tail of angiotensin II (AT(1A)) receptor.

ABSTRACT: In this study, we present data that support the presence of two distinct calmodulin binding sites within the angiotensin II receptor (AT(1A)), at juxtamembrane regions of the N-terminus of the third intracellular loop (i3, amino acids 214-231) and carboxyl tail of the receptor (ct, 302-317). We used bioluminescence resonance energy transfer assays to document interactions of calmodulin with the AT(1A) holo-receptor and GST-fusion protein pull-downs to demonstrate that i3 and ct interact with calmodulin in a Ca²⁺-dependent fashion. The former is a 1-12 motif and the latter belongs to 1-5-10 calmodulin binding motif. The apparent Kd of calmodulin for i3 is 177.0±9.1 nM, and for ct is 79.4±7.9 nM as assessed by dansyl-calmodulin fluorescence. Replacement of the tryptophan (W219) for alanine i

SUBMITTER: Zhang R 

PROVIDER: S-EPMC3673938 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature