Identification and characterization of G beta 3s2, a novel splice variant of the G-protein beta 3 subunit.
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.
Rosskopf
Dieter
D
Institut für Pharmakologie, Universitätsklinikum Essen, D-45122 Essen, Germany. dieter.rosskopf@uni-essen.de
Manthey
Iris
I
Habich
Christiane
C
Kielbik
Marzena
M
Eisenhardt
Andreas
A
Nikula
Christiane
C
Urban
Melanie
M
Kohnen
Stefanie
S
Graf
Eva
E
Ravens
Ursula
U
Siffert
Winfried
W
D000483:Alleles; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D019281:Dimerization; D005786:Gene Expression Regulation; D006321:Heart / Q000502:physiology; D020962:Heterotrimeric GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D011487:Protein Conformation; D021122:Protein Subunits; D017422:Sequence Analysis, DNA
C454420:G-protein beta3 subunit; D021122:Protein Subunits; D020962:Heterotrimeric GTP-Binding Proteins