%0 Journal Article
%T Isoflurane Enhances the Moonlighting Activity of GAPDH: Implications for GABAA Receptor Trafficking
%A Andrew J. Montalbano
%A Christopher S. Theisen
%A Eugene E. Fibuch
%A Norbert W. Seidler
%J ISRN Anesthesiology
%D 2012
%R 10.5402/2012/970795
%X receptor activity is directly modulated by glyceraldehyde 3-phosphate dehydrogenase (GAPDH), a protein with many nonglycolytic moonlighting functions. In addition to playing a role in the phosphorylation of the receptor, GAPDH may also participate in proper receptor trafficking to the plasma membrane. We previously showed that volatile anesthetics affect GAPDH structure and function that may contribute to the manner by which GAPDH modulates the receptor. In the current study, GAPDH interacted with engineered phospholipid-containing vesicles, preferring association with phosphatidylserine over phosphatidylcholine. Phosphatidyl-serine is known to participate in membrane trafficking of transport proteins and to play a role in receptor stability and function. We observed that GAPDH promoted the self-association and fusion of phosphatidyl-serine-rich vesicles as well as decreased membrane fluidity. Isoflurane enhanced each of these GAPDH-mediated events. Isoflurane also increased the binding of GAPDH to the cytoplasmic loop of the receptor. These observations are consistent with the working model of isoflurane playing a role in the trafficking of membrane proteins. This study is the first to implicate GAPDH and isoflurane in the regulation of receptor localization, providing insight into the mechanism of action of anesthesia. 1. Introduction The activity of the receptor is modulated directly by glyceraldehyde 3-phosphate dehydrogenase (GAPDH) [1], which participates in the local production of ATP followed by phosphotransferase activity involving the phosphorylation of the cytoplasmic loop of the ¦Á-subunit of the receptor. There is an increased recognition of GAPDH¡¯s multifunctionality, particularly with regard to neuronal function [2]. We think that in addition to this role (i.e., kinase-dependent phosphorylation of the receptor [1]), GAPDH may also participate in the proper receptor trafficking to the plasma membrane, and perhaps the recycling event. We previously showed that volatile anesthetics affect GAPDH structure and function [3, 4]. Sevoflurane, for example, alters the kinetic properties of GAPDH, and isoflurane affects the oligomeric configuration of the protein. Others have also showed that volatile agents influence the oxidoreductase activity of GAPDH [5, 6]. These observations support the concept that volatile anesthetic agents bind to GAPDH. We propose that the binding of anesthetic agents to GAPDH may contribute to the manner by which GAPDH modulates the receptor. The functional diversity of GAPDH includes the ability of the protein to interact
%U http://www.hindawi.com/journals/isrn.anesthesiology/2012/970795/