Disease relevance of G-ialpha65A

• However, unlike all reported Gi alpha subunit the DG alpha 1-encoded protein is not expected to be a pertussis toxin substrate, because it lacks a cysteine at the appropriate site [1].
• Little or no Gi alpha was detected in other brain regions or in the thoracic ganglion [2].
• However, a Drosophila Gi alpha fusion protein could be detected by these antibodies following expression in E. coli [2].

High impact information on G-ialpha65A

• Microtubule-induced Pins/Galphai cortical polarity in Drosophila neuroblasts [3].
• Their ability to dampen signalling via Galphai-, Galphaq- and Galpha12/13-coupled pathways makes them crucial players in mediating the multitude of cellular processes controlled by heterotrimeric G proteins [4].
• In ric-8 mutants, neither Galphai nor its associated beta-subunit Gbeta13F are localized at the plasma membrane, which leads to their degradation in the cytosol [5].
• Drosophila Ric-8 regulates Galphai cortical localization to promote Galphai-dependent planar orientation of the mitotic spindle during asymmetric cell division [6].
• Further analysis of Gbetagamma and other mutants indicates a predominant role of Partner of Inscuteable-Galphai in spindle orientation [7].

Biological context of G-ialpha65A

• The DG alpha 1 gene is located on band 65C on the left arm of the third chromosome, on the basis of in situ hybridizations to Drosophila salivary gland polytene chromosomes [1].
• A Drosophila melanogaster G protein alpha subunit gene is expressed primarily in embryos and pupae [1].
• A G protein alpha subunit gene has been isolated from a Drosophila melanogaster genomic library using a combination of bovine rod and cone transducin alpha subunit cDNAs as a probe under reduced stringency conditions [1].
• The gene, DG alpha 1, encodes a protein with an amino acid sequence 78% identical to bovine Gi alpha 1 [1].
• A Drosophila melanogaster gene (dgo) encoding a G protein alpha subunit has been isolated by screening genomic and adult head cDNA libraries using bovine transducin alpha subunit cDNA as probe [8].

Anatomical context of G-ialpha65A

• The Gi alpha homolog could not be detected in head membranes by Western blotting, consistent with the negligible levels of expression observed for Gi alpha on Northern blots of head mRNA (Provost et al., 1988) [2].
• Lymantria dispar testes synthesize immunodetectable ecdysteroid in vitro in response to the brain peptide, testis ecdysiotropin (TE), acting primarily via a cascade involving Gi protein, diacyl glycerol, and phosphokinase C [9].
• This interaction and the coexpression of LOCO and Galphai suggests a function of G-protein signalling for glial cell development [10].
• Initially granules containing Gi alpha are present throughout the embryonic cortex but during nuclear cleavage they become concentrated at the posterior pole and are lost by the blastoderm stage [11].

Associations of G-ialpha65A with chemical compounds

• Reconstitution of purified squid PLC with an AlF(-)-activated 44-kDa G protein alpha subunit extracted from squid photoreceptor membranes resulted in a significant increase in PIP2 hydrolysis over a range of Ca2+ concentrations while reconstitution with mammalian Gt alpha or Gi 1 alpha was without effect [12].

Physical interactions of G-ialpha65A

• RESULTS: A novel 70 kDa protein called Partner of Inscuteable (Pins) and a heterotrimeric G-protein alpha subunit were found to bind specifically to the functional domain of Inscuteable in vivo [13].
• Drosophila Ric-8 is a cytoplasmic protein that binds both the GDP- and GTP-bound form of the G-protein alpha-subunit Galphai [5].

Other interactions of G-ialpha65A

• Distinct roles of Galphai and Gbeta13F subunits of the heterotrimeric G protein complex in the mediation of Drosophila neuroblast asymmetric divisions [14].
• The schistosome clone contains the putative site for ADP-ribosylation by cholera toxin found in Gs alpha but does not contain the ADP-ribosylation site for pertussis toxin present in Gi alpha [15].
• From these results we conclude that Gi alpha redistribution to the posterior pole depends on maternal factors involved in the localization of the posterior morphogen nanos [11].
• Mutations that eliminate anterior structures bicoid, swallow, and exuperantia did not prevent the posterior accumulation of Gi alpha [11].
• Likewise, embryos from mothers with dominant gain of function mutations in the Bicaudal D gene show normal polarization of Gi alpha granules [11].

Analytical, diagnostic and therapeutic context of G-ialpha65A

• From the antennae of the moth Mamestra brassicae, we have identified a lepidopteran G protein alpha subunit belonging to the Gq family, through immunological detection in crude antennal extract and antennal primary cell cultures, followed by molecular cloning [16].
• All six PCR products are unique at the nucleotide level, but the translation products of the three Galpha q-like partial clones (Sf9-Galpha 1, Ld-Galpha 1, and Hi5-Galpha 1) are identical, as are the translation products of the three Galpha i-like partial clones (Sf9-Galpha 2, Ld-Galpha 2, and Hi5-Galpha 2) [17].

References