Effects of βα subunits of signal transducing G proteins on the activation of p38

다국어 초록 (Multilingual Abstract)

Heterotrimeric guaine nucleotide binding proteins (G proteins) transduce extracellular signalr into intracellular responses by coupling receptors and effectors. The activated G proteins regulate the activity of ion channels and enzymes such as adenylate cyclase and phospholipase C, and they also stimulate mitogen activated protein kinase (MAPK) pathways artivated by receptor tyrosine kinase stimulated by various growth hormores. Both the alpha and beta-gamma complex of the G protein are involved in the activatioil of MAPKS. The G?r mediates activation of extracellular signal-regulated kinase (MAPK/ERK), c-Jun N-terminal kinase/stress activated protein kinase (JNK/SAPK), p38 MAPK. However, the difference of the MAPK activating capacity of G?r among beta subunit isoforms is not known yet. Thus we have overexpressed different beta subunits in COS-1 cells and the activation of JNK/SAPK and p38 MAPK by ultraviolet irradiation was analyaed. When beta isoforms of the G protein was cotransfected with Gr2, all the beta isoforms except ?3 were overexpressed. Ultraviolet light stimulated JNK/SAPK activity was increased in the COS-1 cells expressing ?2 and ?4 isoforms, but in the cells expressing ?1 and ?5. The COS-1 cells overexpressing ?1 and ?5 isoforms showed increase in the ultraviolet light stimulated p38 MAPK activity. Our results demonstrated that each beta subunit has different potential to activate either JNK/SAPK or p38 MAPK, and suggested that all the tested beta isoforms except beta 3 form functional complexes with gamma 2 subunit of G proteins.

목차 (Table of Contents)

• Abstract
• 1.Introduction
• 2.Materials and Methods
• 3.Results and Discussions
• References