No abstract

The angiotensin II type I (AT 1 ) receptor mediates regulation of blood pressure and water-electrolyte balance by Ang II. Substitution of Gly for Asn 111 of the AT 1 receptor constitutively activates the receptor leading to Gq-coupled IP 3 production independent of Ang II binding. The Ang II-activated conformation of the AT1 N111G receptor was proposed to be similar to that of the wild-type AT 1 receptor, although, various aspects of the Ang II-induced conformation of this constitutively active mutant receptor have not been systematically studied. Here, we provide evidence that the conformation of the active state of the wild-type and the constitutively active AT 1 receptors are different. Upon Ang II binding an activated conformation of the wild-type AT 1 receptor activates G protein and recruits barrestin. In contrast, the agonist-bound AT1 N111G mutant receptor preferentially couples to Gq and is inadequate in b-arrestin recruitment.

Glucagon like peptide-1 (GLP-1) regulates glucose mediated-insulin secretion, nutrient accumulation, and β-cell growth. Despite the potential therapeutic usage for type 2 diabetes (T2D), GLP-1 has a short half-life in vivo (t1/2 ＜2 min). In an attempt to prolong half-life, GLP-1 fusion proteins were genetically engineered: GLP-1 human serum albumin fusion (GLP-1/HSA), AGLP-1/HSA which has an additional alanine at the N-terminus of GLP-1, and AGLP-1-L/HSA, in which a peptide linker is inserted between AGLP-1 and HSA. Recombinant fusion proteins secreted from the Chinese Hamster Ovary-K1 (CHO-K1) cell line were purified with high purity (＞96%). AGLP-1 fusion protein was resistant against the dipeptidyl peptidase-IV (DPP-IV). The fusion proteins activated cAMP-mediated signaling in rat insulinoma INS-1 cells. Furthermore, a C57BL/6N mice pharmacodynamics study exhibited that AGLP-1-L/HSA effectively reduced blood glucose level compared to AGLP-1/HSA. [BMB Reports 2013; 46(12): 606-610]