Expression of G-protein alpha subunit genes in the vestibular periphery of Rattus norvegicus and their chromosomal mapping.
OBJECTIVE
Heterotrimeric G-proteins play an important role in mediating signals transduced across the cell membrane by membrane-bound receptors. The precise role of G-proteins and their coupled receptors in the physiology of the vestibular neuroepithelium is not well understood. The purpose of this study was to better define the role of these proteins by examining their expression in the rat vestibular periphery and characterizing their chromosomal location.


METHODS
To characterize G-protein alpha subunit gene expression in the target tissue of interest, we performed polymerase chain reaction (PCR) using degenerate G-protein primers corresponding to conserved regions in the G-protein alpha subunit coding sequence on a normalized rat vestibular cDNA library. PCR amplicons were cloned and 50 clones were randomly selected and sequenced. Radiation hybrid (RH) mapping was used to determine the chromosomal location of G alpha(olf) and two previously identified G-protein alpha subunits--G alpha(i2) and G alpha(i2(vest))--in the rat genome.


RESULTS
The following G-protein alpha subunits were identified in the normalized cDNA library: G alpha(olf), G alpha(s), G alpha(o) and G alpha(s2). G alpha(olf) maps to chromosome 18 between markers D18Mit17b and D18Mgh2. G alpha(i2) maps to chromosome 8 between markers D8Rat65 and D8Mgh2. G alpha(i2(vest)) maps to chromosome 1 between markers D1Rat132 and D1Rat202. These chromosomal locations in the rat genome are syntenic to chromosomal regions in which the homologous G-protein alpha subunit genes have been localized in the human and mouse genomes, further validating RH mapping as an effective and accurate tool. We were unable to RH map the location of G alpha(o) due to its extensive homology with the hamster gene.


CONCLUSIONS
The characterization of G-protein alpha subunit gene expression in the vestibular periphery and the chromosomal localization of these genes in the rat revealed that a diverse group of these second messengers are expressed.
Cioffi
Joseph A
JA
Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Erbe
Christy B
CB
Raphael
Richard
R
Kwitek
Anne E
AE
Tiwari
Umesh K
UK
Jacob
Howard J
HJ
Popper
Paul
P
Wackym
Phillip A
PA
D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary; D005260:Female; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics* / Q000502:physiology; D015870:Gene Expression; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000502:physiology; D008297:Male; D016133:Polymerase Chain Reaction; D021101:Radiation Hybrid Mapping; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D014722:Vestibule, Labyrinth / Q000502:physiology*
D018076:DNA, Complementary; D044385:GTP-Binding Protein alpha Subunits; D043562:Receptors, G-Protein-Coupled; D020962:Heterotrimeric GTP-Binding Proteins