Identification and characterization of Gbeta3s2, a novel splice variant of the G-protein beta3 subunit

Abstract

The T-allele of a polymorphism (C825T) in the gene for the G-protein beta 3 subunit (GNB3) is associated with cardiovascular and metabolic disorders, distinct cellular features and altered drug responses. The molecular mechanisms that give rise to this complex phenotype have been linked to the occurrence of G beta 3s, a splice variant of GNB3. G beta 3s is predominantly expressed in cells with the 825T-allele. In the present study we describe the identification and characterization of an additional G beta 3 splice variant referred to as G beta 3s2. Its mRNA is expressed in heart, blood cells and tumour tissue, and its expression is also tightly associated with the GNB3 825T-allele. G beta 3s2 is generated by alternative splicing using non-canonical splice sites. G beta subunits belong to the family of propeller proteins and consist of seven regular propeller blades. Transcripts for G beta 3s2 are lacking 129 bp of the coding sequence of the wild-type G beta 3 protein. Thus the predicted structure consists of only six propeller blades, which resembles the structure of G beta 3s. Co-immunoprecipitation analyses indicated that G beta 3s2 dimerizes with different G gamma subunits, e.g. G gamma 5, G gamma 8(C) and G gamma 12. In Sf9 insect cells, expression of G beta 3s2 together with G gamma 12 enhances receptor-stimulated activation of G alpha(i2). Expression of G beta 3s2 in mammalian cells activated the mitogen-activated protein kinase cascade. Together, these results suggest that G beta 3s2 is a biologically active G beta variant which may play a role in the manifestation of the complex phenotype associated with the 825T-allele.

Association between a G-protein β3 subunit gene polymorphism and the symptomatology and treatment responses of major depressive disorders

“…Evidence from transient-expression experiments suggests that Gb3s is a biologically active protein that enhances signal transduction. 3,16,17 Recently, Rosskopf et al 18 reported that Gb3s-containing G protein results in an increased number of activated Gas and free Gbg dimers, which subsequently activate the downstream effector systems.…”

Genetics of arterial hypertension and hypotension

“…Mechanistically, this polymorphism is associated with the occurrence of two alternative splice variants termed Gβ3s and Gβ3s2 ( Fig. 16; Rosskopf et al 2003a). Protein crystallization studies have resolved the structure of the Gβγ dimer.…”

Effects of the G protein β3-subunit gene C825T polymorphism: should hypotheses regarding the molecular mechanisms underlying enhanced G protein activation be revised? Focus on “A splice variant of the G protein β3-subunit implicated in disease states does not modulate ion channels”

“…A second aberrant splicing process was also identified which affects exon 10 (in which the C825T polymorphism is located) giving rise to a splice variant referred to as G␤3-s2. (20). By means of RT-PCR this splice variant was detected in human heart, T cells, neutrophils, peripheral blood lymphocytes, and bladder carcinoma predominantly in cells and tissues from 825T allele carriers (20).…”

“…(20). By means of RT-PCR this splice variant was detected in human heart, T cells, neutrophils, peripheral blood lymphocytes, and bladder carcinoma predominantly in cells and tissues from 825T allele carriers (20).…”