MECHANISMS OF ALPHA2 ADRENERGIC RECEPTOR FUNCTION

ALPHA2 肾上腺素受体功能机制

• 批准号: 2460092
• 负责人: Stephen B Liggett
• 金额: $ 25.36万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2460092
• 关键词: G protein; alpha adrenergic agent; alpha adrenergic receptor; biological signal transduction; chimeric proteins; clone cells; immunoelectron microscopy; phosphorylation; protein kinase; protein structure function; receptor coupling; receptor expression; receptor sensitivity; site directed mutagenesis; transfection

Alpha-2-adrenergic receptors (alpha-2-AR) are cell surface receptors which upon binding catecholamines signal to the interior of the cell via G proteins. Alpha-2-AR are expressed in virtually every organ system and are known to play important roles in cardiovascular, pulmonary, renal, hepatic, metabolic, and central nervous system functions. Alpha-2-ARs have also been implicated in a number of pathologic processes and are the targets for pharmacologic agents in the treatment of a number of diseases. The long-term objective of this project is to understand the relationships between the molecular structures of these receptors and their functions. These goals will be carried out primarily by site-directed mutagenesis of the cDNAs encoding for the wild-type alpha-2-AR subtypes (alpha-2C10, alpha-2-C4, and alpha-2-C2), followed by recombinant expression in mammalian cells. This allows for directly comparing a given function between wild-type and mutated receptor and delineating a structure/function relationship. In Specific Aim 1, the role of G protein coupled receptor kinases in the phosphorylation of alpha-2-ARs during short-term agonist promoted desensitization will be studied. In Specific Aim 2, the phosphorylation domains of the alpha-2-AR will be mapped by assessing functional short-term agonist promoted desensitization and receptor phosphorylation in wild-type and alpha-2-ARs with mutated residues in regions that we suspect are sites for phosphorylation. In Specific Aim 3, the molecular features of the alpha- 2-AR subtypes which are responsible for the differences in agonist- promoted desensitization and phosphorylation observed between the three subtypes will be determined. Specific Aim 4 explores the mechanism of receptor sequestration (internalization) and downregulation, two key events which occur during long-term agonist promoted regulation of alpha- 2-ARs. Here, the subcellular events of receptor trafficking and processing will be examined using immunoelectron microscopy. In Specific Aim 5, the molecular determinants of alpha-2-AR sequestration and downregulation will be studied using site-directed mutagenesis of regions suspected to be involved in these processes including sites for palmitoylation, glycosylation, and phosphorylation, and regions involved with G protein coupling. In Specific Aim 6, the domains of the alpha-2- AR responsible for coupling to G1 and G2 will be delineated by both deletion and chimeric substitution mutagenesis. In Specific Aim 7 the molecular determinants of the observed differences in G2 coupling between the three alpha-2-AR subtypes will be determined. The results of these studies will help to determine at a fundamental level how alpha-2-AR carry out their signal transduction, how they are regulated, and how they can be modulated by therapeutic agents.

α -2-肾上腺素能受体（α -2- ar）是细胞表面受体