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Gene Review

YPT31  -  Rab family GTPase YPT31

Saccharomyces cerevisiae S288c

Synonyms: GTP-binding protein YPT31/YPT8, Rab GTPase YPT31, YER031C, YPT8
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High impact information on YPT31


Biological context of YPT31

  • Cells deleted for the YPT31 gene and carrying a conditional ypt32 mutation exhibit protein transport defects in the late exocytic pathway, but not in vacuolar protein sorting [3].
  • Here we report that mutant alleles of YPT31 and YPT32, whose gene products have a reduced affinity for GTP, are able to suppress the dominant lethal phenotype of YPT1(N121I) [4].
  • Increasing the gene dosage of YPT31/32 also suppressed lethality resulting from deletion of TRS130 or TRS120 but not three other essential TRAPP subunit-encoding genes [5].
  • We show that like Rcy1, Ypt31/32 regulate the coupled phosphorylation and recycling of the plasma membrane v-SNARE Snc1 [6].
  • This ORF also has a striking similarity to a putative 43 kDa zinc finger protein encoded by an ORF (YEL8) immediately downstream of YPT8, raising the possibility that a region between VAM7 and SPM2 on chromosome VII arose as a duplication of the YPT8-YEL8 region of chromosome V, followed by a translocation [7].

Anatomical context of YPT31

  • In yeast, Ypt1p has an essential function late in endoplasmic reticulum (ER) to Golgi transport, and the redundant Ypt31/Ypt32 GTPases have been proposed to act in transport through and/or from the Golgi [4].
  • From the phenotypic alterations observed in ypt31 and ypt32 mutants, it seems likely that the two GTPases are involved in intra-Golgi transport or in the formation of transport vesicles at the most distal Golgi compartment [8].
  • We propose that the Ypt31p/32p-Rcy1p pathway regulates putative phospholipid translocases to promote formation of vesicles destined for the trans-Golgi network from early endosomes [9].

Associations of YPT31 with chemical compounds

  • We propose that multiple stage-specific signals, which may include Pik1p/PtdIns(4)P, TRAPPII and Gyp2p, impinge upon Ypt31 signaling to regulate Golgi secretory function [10].

Regulatory relationships of YPT31

  • Although unable to suppress defects in several alleles of ARF1, increasing the gene dosage of YPT31/32 suppressed the cold sensitivity of gcs1(-), an Arf GTPase-activating protein (GAP) [5].
  • Furthermore, Ypt31/32 regulates the polarized localization and half-life of Rcy1 [6].
  • We further demonstrate that TRAPPII specifically functions in a Ypt31p-dependent pathway and identify Gyp2p as the first biologically relevant GTPase activating protein for Ypt31p [10].
  • We propose that Ypt31/32p have a role in regulating the delivery of Chs3p to the plasma membrane and deposition of chitin at the cell surface [11].

Other interactions of YPT31

  • Genetic interactions link ARF1, YPT31/32 and TRS130 [5].
  • Thus, these genetic interactions provide initial evidence for linkage of Arf and TRAPP signalling and for Ypt31/32 proteins functioning downstream of both components in the TRAPP complex and of Arf signalling via the Gcs1 Arf GAP [5].
  • Here we report the identification of a new member of the Sec7-domain family, SYT1, as a high-copy suppressor of a ypt31/32 mutation [12].
  • Our data suggest a mechanistic involvement for Pik1p with a specific subset of Golgi-associated proteins, including the Ypt31p rab-GTPase and the TRAPPII protein complex, to regulate protein trafficking through the secretory pathway [10].
  • The F-box protein Rcy1, which mediates plasma membrane recycling, is identified here as a downstream effector of the Ypt31/32 GTPase pair because it binds active GTP-bound Ypt31/32 and colocalizes with these GTPases on late Golgi and endosomes [6].

Analytical, diagnostic and therapeutic context of YPT31

  • In accordance with this, indirect immunofluorescence using affinity-purified anti-Ypt31p antibodies gave a punctate staining similar to that observed with Golgi-located proteins [8].


  1. Ypt32 recruits the Sec4p guanine nucleotide exchange factor, Sec2p, to secretory vesicles; evidence for a Rab cascade in yeast. Ortiz, D., Medkova, M., Walch-Solimena, C., Novick, P. J. Cell Biol. (2002) [Pubmed]
  2. Specific binding to a novel and essential Golgi membrane protein (Yip1p) functionally links the transport GTPases Ypt1p and Ypt31p. Yang, X., Matern, H.T., Gallwitz, D. EMBO J. (1998) [Pubmed]
  3. Two new Ypt GTPases are required for exit from the yeast trans-Golgi compartment. Jedd, G., Mulholland, J., Segev, N. J. Cell Biol. (1997) [Pubmed]
  4. Functional implications of genetic interactions between genes encoding small GTPases involved in vesicular transport in yeast. Yoo, J.S., Grabowski, R., Xing, L., Trepte, H.H., Schmitt, H.D., Gallwitz, D. Mol. Gen. Genet. (1999) [Pubmed]
  5. Genetic interactions link ARF1, YPT31/32 and TRS130. Zhang, C.J., Bowzard, J.B., Greene, M., Anido, A., Stearns, K., Kahn, R.A. Yeast (2002) [Pubmed]
  6. Ypt31/32 GTPases and their novel F-box effector protein Rcy1 regulate protein recycling. Chen, S.H., Chen, S., Tokarev, A.A., Liu, F., Jedd, G., Segev, N. Mol. Biol. Cell (2005) [Pubmed]
  7. Lambda clone B22 contains a 7676 bp genomic fragment of Saccharomyces cerevisiae chromosome VII spanning the VAM7-SPM2 intergenic region and containing three novel transcribed open reading frames. Kail, M., Jüttner, E., Vaux, D. Yeast (1996) [Pubmed]
  8. Two GTPase isoforms, Ypt31p and Ypt32p, are essential for Golgi function in yeast. Benli, M., Döring, F., Robinson, D.G., Yang, X., Gallwitz, D. EMBO J. (1996) [Pubmed]
  9. Endocytic recycling in yeast is regulated by putative phospholipid translocases and the ypt31p/32p-rcy1p pathway. Furuta, N., Fujimura-Kamada, K., Saito, K., Yamamoto, T., Tanaka, K. Mol. Biol. Cell (2007) [Pubmed]
  10. Synthetic genetic array analysis of the PtdIns 4-kinase Pik1p identifies components in a Golgi-specific Ypt31/rab-GTPase signaling pathway. Sciorra, V.A., Audhya, A., Parsons, A.B., Segev, N., Boone, C., Emr, S.D. Mol. Biol. Cell (2005) [Pubmed]
  11. Ypt32p regulates the translocation of Chs3p from an internal pool to the plasma membrane. Ortiz, D., Novick, P.J. Eur. J. Cell Biol. (2006) [Pubmed]
  12. Genetic interactions in yeast between Ypt GTPases and Arf guanine nucleotide exchangers. Jones, S., Jedd, G., Kahn, R.A., Franzusoff, A., Bartolini, F., Segev, N. Genetics (1999) [Pubmed]
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