The G protein beta subunit Gpb1 of Schizosaccharomyces pombe is a negative regulator of sexual development

Mol Gen Genet. 1996 Aug 27;252(1-2):20-32. doi: 10.1007/BF02173201.


A Schizosaccharomyces pombe homolog of mammalian genes encoding G protein beta subunits, gpb1+, was cloned by the polymerase chain reaction using primer pairs that correspond to sequences conserved in several G beta genes of other species followed by screening of genomic and cDNA libraries. The gpb1 gene encodes 317 amino acids that show 47% homology with human G beta 1 and G beta 2 and 40% homology with Saccharomyces cerevisiae G beta protein. Disruption of the gpb1 gene indicated that this gene is not required for vegetative cell growth. However, gpb1-disrupted haploid cells mated and sporulated faster than wild-type cells, both in sporulation (MEA) and in complex medium (YE): when examined 23 h after transfer to sporulation medium, 35% of gpb1-disrupted haploid pairs had undergone conjugation and sporulation, whereas only 3-5% of wild-type haploid pairs had done so. Overexpression of the gpb1 gene suppressed this facilitated conjugation and sporulation phenotype of gpb1-disrupted cells but did not cause any obvious effect in wild-type cells. Co-disruption of one of the two S. pombe G alpha-subunit genes, gpa2, in the gpb1-disrupted cells did not change the accelerated conjugation and sporulation phenotype of the gpb1- cells. However, co-disruption of the ras1 gene abolished the gpb1- phenotype. These results suggest that Gpb1 is a negative regulator of conjugation and sporulation that apparently works upstream of Ras1 function in S. pombe. The possible relationship of Gpb1 to two previously identified, putative G alpha proteins of S. pombe is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Northern
  • Cloning, Molecular
  • Conjugation, Genetic
  • DNA Primers
  • Electrophoresis, Agar Gel
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics*
  • Fungal Proteins / physiology*
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / genetics*
  • GTP-Binding Proteins / physiology*
  • Genes, Fungal
  • Heterotrimeric GTP-Binding Proteins*
  • Molecular Sequence Data
  • Phenotype
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces / physiology
  • Schizosaccharomyces pombe Proteins*
  • Sequence Homology, Amino Acid
  • Spores, Fungal / physiology


  • DNA Primers
  • Fungal Proteins
  • Schizosaccharomyces pombe Proteins
  • git5 protein, S pombe
  • GTP-Binding Proteins
  • Heterotrimeric GTP-Binding Proteins

Associated data

  • GENBANK/L28061