Interaction of PICK1 with C-terminus of growth hormone-releasing hormone receptor (GHRHR) modulates trafficking and signal transduction of human GHRHR.

Release of growth hormone (GH) from the somatotroph is regulated by binding GH-releasing hormone (GHRH) to its cognate receptor (GHRHR), one of the members of the G protein-coupled receptor (GPCR) superfamily. Proteins bound to the carboxy (C)-terminus of GPCR have been reported to regulate intracellular trafficking and function of the receptor; however, no functionally significant protein associated with GHRHR has been reported. We have identified a protein interacting with C-kinase 1 (PICK1) as a binding partner of GHRHR.

PTH/PTH-related protein receptor interacts directly with Tctex-1 through its COOH terminus.

COOH-terminal cytoplasmic domains of G protein-coupled receptors (GPCRs) have been shown to carry determinants that control their cell surface localization, internalization, and recycling. In attempts to seek cellular proteins that mediate these processes of PTH/PTH-related protein receptor (PTHR), one of the class B GPCRs, we have found that Tctex-1, a 14kDa light chain of cytoplasmic dynein motor complex, interacts with the COOH-terminal tail of the receptor. A 34-amino-acid stretch of the receptor responsible for binding to Tctex-1 has a bipartite structure consisting of a motif previously implicated in binding of some proteins to Tctex-1 and a putative new consensus sequence.