8.A.92.1.15
Heteromeric 7 TMS glucose receptors coupled with two large G-proteins, Ras1 and Ras2 of 309 and 3322 aas, respectively, both with 1 N-terminal TMS. One subunit is called the guanine nucleotide-binding protein, alpha-2 subunit, Gpa2 of 449 aas and 6 - 8 TMSs, and the other is called the guanine nucleotide binding protein, GPR1, of 961 aas and 6 - 8 TMSs. They comprise a hetero-tri- or tetra-meric guanine nucleotide-binding protein (G protein) complex, involved in glucose-induced cAMP signaling. These two cognate transmembrane G-protein receptors bind to each other, which sense extracellular carbon sources, and activate cAMP-PKA signaling to govern diploid pseudohyphal differentiation and haploid invasive growth. The G protein beta-mimic proteins, GPB1 (Q08886) and GPB2 (P39717) inhibit GPA2-GPR1 coupling, probably to reduce signaling in the absence of glucose (Versele et al. 1999; Harashima and Heitman 2005). The S. cerevisiae Ras proteins, amoung other things, modulate the activity of the adenylate cyclase catalytic subunit and therefore alter the biosynthesis of cyclic-AMP. A multi-omics analysis of multiple glucose-sensing receptor systems in yeast has appeared (Li et al. 2022).