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Five Different Phosphorylation Sites in the C‐Terminal regulate a1b‐Adrenergic Receptor Signaling and Regulations
Author(s) -
Hernández David Alejandro
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.555.15
Subject(s) - g protein coupled receptor , g protein coupled receptor kinase , internalization , microbiology and biotechnology , phosphorylation , g protein , protein kinase c , phospholipase c , biochemistry , chemistry , receptor , signal transduction , biology
The G protein‐coupled receptors (GPCRs) transmit a variety of signals across the cell membrane and regulate cellular activity via the intermediary role of guanine nucleotide regulatory proteins (G proteins). Among these receptors, the a 1B ‐Adrenergic (a 1B ‐AR) receptor mediates the effects of catecholamines, like epinephrine and norepinephrine, through coupling to Gq. The activation of the a 1B ‐AR causes polyphosphoinositide hydrolysis catalyzed by phospholipase C (PLC), generating inositol trisphosphate and diacylglycerol, which together lead to calcium signaling and protein kinase C (PKC) activation. Subsequently, receptors are phosphorylated, triggering their desensitization and internalization, a process mediated by members of the G proteins‐coupled receptor kinases (GRK) family and/or by PKC. It is currently known the a 1B ‐AR is phosphorylated in two separate groups of serine residues in the carboxyl terminal tail, one by PKC (S 396 and S 402 ) and one by GRK (S 406 , S 410 and S 412 ) during the desensitization and internalization of the receptor. The mutation of these residues prevents agonist induced desensitization and blocks the receptor internalization into the plasma membrane. Because the role of these specific sites remains unknown in different down‐process of the a 1B ‐AR, we investigated the importance of phosphorylation by PKC and GRK in calcium desensitization signal, mitogen activated protein kinases (MAPK) pathway and receptor phosphorylation. To achieve this,, we generated three site specific mutants of the a 1B ‐AR in which the serine residues phosphorylated by the two kinases were mutated to alanine, alone or in tandem. We found that any of these mutations in the phosphorylation sites produces changes in the heterologous desensitization of the receptor detected by intracellular calcium response and in the activation of the MAPK, when compared to the wild type. Finally, we obtained clear differences in the phosphorylation pattern of each mutant during noradrenaline stimulation. Support or Funding Information Partially supported by Grants from CONACYT (253156 and 882) and DGAPA (IN200915). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .