IMMUNOLOGICAL AND MOLECULAR CHARACTERIZATION OF G0-ALPHA-LIKE PROTEINS IN THE DROSOPHILA CENTRAL NERVOUS-SYSTEM

  • 5 November 1989
    • journal article
    • research article
    • Vol. 264  (31) , 18552-18560
Abstract
The .alpha. subunits of heterotrimeric G proteins are responsible for the coupling of receptors for a wide variety of stimuli to a number of intracellular effector systems. In the nervous system of vertebrates, high levels of a specific class of G protein (Go.alpha.) are expressed. The .alpha. subunit of Go serves as a substrate for modification by pertussis toxin (PTX). In this report, we demonstrate that the Drosphila heads contain high levels of a 40-kDa PTX substrate. Modification of this protein by PTX is modulated in a manner similar to that observed for vertebrate G proteins. The PTX substrate in Drosphila is also recognized specifically by antibodies raised against peptide sequences found specifically in vertebrate Go.alpha.. Vertebrate Go.alpha. probes were used to identify a Drosphila cDNA coding for a potential PTX substrate with high sequence identity (82%) to vertebrate Go.alpha.. An additional cDNA coding for a related Go.alpha. has also been isolated. The two cDNAs differ only in the 5''-untranslated and amino-terminal regions of the protein. This observation, in addition to Northern analysis, suggests that alternate splicing may generate a variety of Go.alpha.-like proteins in Drosphila. In situ hybridization of specific probes to tissue sections indicates that the mRNAs coding for Go.alpha.-like proteins in Drosphila are expressed primarily in neuronal cell bodies and, at lower levels, in the eyes.