The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)



Gene Review

SEC4  -  Rab family GTPase SEC4

Saccharomyces cerevisiae S288c

Synonyms: Ras-related protein SEC4, SRO6, Suppressor of RHO3 protein 6, YFL005W
Welcome! If you are familiar with the subject of this article, you can contribute to this open access knowledge base by deleting incorrect information, restructuring or completely rewriting any text. Read more.

Disease relevance of SEC4

  • In the present study, purified recombinant Sec4 and Ypt1 proteins expressed in E. coli have been used as substrates to determine if GTPase activating proteins (GAPs) directed toward these proteins are present in rat pancreas [1].

High impact information on SEC4

  • A functional fusion of Sec3 protein with green fluorescent protein (Sec3-GFP) localizes to the site of polarized exocytosis for each cell-cycle stage, where it colocalizes with Sec4p and Sec8p [2].
  • Sec9 is a SNAP-25-like component of a yeast SNARE complex that may be the effector of Sec4 function in exocytosis [3].
  • A set of 11 clones encoding putative GTP binding proteins highly homologous to the yeast YPT1/SEC4 gene products have been isolated from an MDCK cell cDNA library [4].
  • In all post-Golgi blocked sec mutants, Sec4p is predominantly associated with the secretory vesicles that accumulate as a result of the secretory block [5].
  • Sec4p is synthesized as a soluble protein that rapidly (t1/2 less than or equal to 1 min) and tightly associates with secretory vesicles and the plasma membrane by virtue of a conformational change of a covalent modification [5].

Biological context of SEC4

  • All phenotypes of the temperature-sensitive sec2 alleles are partially suppressed by duplication of the SEC4 gene, but the lethality of a sec2 disruption is not suppressed [6].
  • SEC4 is an essential gene encoding a small GTPase that is involved in Golgi to cell surface transport in Saccharomyces cerevisiae and is a paradigm for studies on the mode of action of Rab proteins [7].
  • Sec8p and Sec15p are components of a plasma membrane-associated 19.5S particle that may function downstream of Sec4p to control exocytosis [8].
  • On the amino acid sequence level, and particularly with respect to known small G protein specificity domains, YptV1p and YptC1p are the closest algal analogs of yeast Ypt1p, with 70% overall identity and identical effector regions, but YptV2p is only 55% identical to Ypt1p, and its effector domain resembles that of Sec4p [9].
  • To study the regulation of membrane traffic in epithelial cells, a set of 11 clones encoding proteins similar to the YPT1/SEC4 products were isolated from an MDCK (Madin-Darby canine kidney) cell cDNA library [10].

Anatomical context of SEC4


Associations of SEC4 with chemical compounds

  • The Sec2p NH(2) terminus encodes an exchange factor for the Rab protein Sec4p [13].
  • None of the D. salina GTP-binding proteins reacted positively with polyclonal antibodies raised against SEC4, rab1 or rab6 proteins [14].
  • In mammalian cells the effects of a non-hydrolysable GTP analogue, GTP-gamma S, on different transport events have suggested that they also have proteins functionally related to yeast Sec4p and Ypt1p [15].
  • Here we show that the yeast Ypt1 and Sec4 proteins, essential components of the vesicular transport machinery, allow unimpaired vesicular transport when permanently fixed to membranes by membrane-spanning domains replacing their two C-terminal cysteine residues [16].
  • To test the role of GTP hydrolysis in Sec4 function, we constructed a mutation, Q-79----L, analogous to the oncogenic mutation of Q-61----L in Ras, in a region of Sec4 predicted to interact with the phosphoryl group of GTP [17].

Regulatory relationships of SEC4

  • The S.pombe ypt2 gene under control of the S.cerevisiae GAL10 promoter is able to suppress the temperature-sensitive phenotype of a S. cerevisiae sec4 mutant, indicating a functional similarity of these GTP-binding proteins from the two very distantly related yeasts [18].
  • Overexpression of Mso1 lacking this domain (Mso1-(1-193)) inhibited the growth of cells bearing an attenuated Sec4 GTPase [19].
  • GAL1-regulated expression plasmids carrying the mutant sec4 allele (pS28N) had minimal effects in glucose-incubated C. albicans transformants, but six of nine transformants tested grew very slowly in galactose [20].

Other interactions of SEC4


Analytical, diagnostic and therapeutic context of SEC4


  1. Distinct and specific GAP activities in rat pancreas act on the yeast GTP-binding proteins Ypt1 and Sec4. Jena, B.P., Brennwald, P., Garrett, M.D., Novick, P., Jamieson, J.D. FEBS Lett. (1992) [Pubmed]
  2. Sec3p is a spatial landmark for polarized secretion in budding yeast. Finger, F.P., Hughes, T.E., Novick, P. Cell (1998) [Pubmed]
  3. Sec9 is a SNAP-25-like component of a yeast SNARE complex that may be the effector of Sec4 function in exocytosis. Brennwald, P., Kearns, B., Champion, K., Keränen, S., Bankaitis, V., Novick, P. Cell (1994) [Pubmed]
  4. Localization of low molecular weight GTP binding proteins to exocytic and endocytic compartments. Chavrier, P., Parton, R.G., Hauri, H.P., Simons, K., Zerial, M. Cell (1990) [Pubmed]
  5. A GTP-binding protein required for secretion rapidly associates with secretory vesicles and the plasma membrane in yeast. Goud, B., Salminen, A., Walworth, N.C., Novick, P.J. Cell (1988) [Pubmed]
  6. Sec2 protein contains a coiled-coil domain essential for vesicular transport and a dispensable carboxy terminal domain. Nair, J., Müller, H., Peterson, M., Novick, P. J. Cell Biol. (1990) [Pubmed]
  7. Interactions of nucleotide release factor Dss4p with Sec4p in the post-Golgi secretory pathway of yeast. Collins, R.N., Brennwald, P., Garrett, M., Lauring, A., Novick, P. J. Biol. Chem. (1997) [Pubmed]
  8. Sec8p and Sec15p are components of a plasma membrane-associated 19.5S particle that may function downstream of Sec4p to control exocytosis. Bowser, R., Müller, H., Govindan, B., Novick, P. J. Cell Biol. (1992) [Pubmed]
  9. Structure-function analysis of small G proteins from Volvox and Chlamydomonas by complementation of Saccharomyces cerevisiae YPT/SEC mutations. Fabry, S., Steigerwald, R., Bernklau, C., Dietmaier, W., Schmitt, R. Mol. Gen. Genet. (1995) [Pubmed]
  10. Molecular cloning of YPT1/SEC4-related cDNAs from an epithelial cell line. Chavrier, P., Vingron, M., Sander, C., Simons, K., Zerial, M. Mol. Cell. Biol. (1990) [Pubmed]
  11. 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]
  12. Expression and localization of two low molecular weight GTP-binding proteins, Rab8 and Rab10, by epitope tag. Chen, Y.T., Holcomb, C., Moore, H.P. Proc. Natl. Acad. Sci. U.S.A. (1993) [Pubmed]
  13. The role of the COOH terminus of Sec2p in the transport of post-Golgi vesicles. Elkind, N.B., Walch-Solimena, C., Novick, P.J. J. Cell Biol. (2000) [Pubmed]
  14. Intracellular translocation of a 28 kDa GTP-binding protein during osmotic shock-induced cell volume regulation in Dunaliella salina. Memon, A.R., Herrin, D.L., Thompson, G.A. Biochim. Biophys. Acta (1993) [Pubmed]
  15. Small GTP-binding protein associated with Golgi cisternae. Goud, B., Zahraoui, A., Tavitian, A., Saraste, J. Nature (1990) [Pubmed]
  16. Functionality and specific membrane localization of transport GTPases carrying C-terminal membrane anchors of synaptobrevin-like proteins. Ossig, R., Laufer, W., Schmitt, H.D., Gallwitz, D. EMBO J. (1995) [Pubmed]
  17. Hydrolysis of GTP by Sec4 protein plays an important role in vesicular transport and is stimulated by a GTPase-activating protein in Saccharomyces cerevisiae. Walworth, N.C., Brennwald, P., Kabcenell, A.K., Garrett, M., Novick, P. Mol. Cell. Biol. (1992) [Pubmed]
  18. Structural and functional analysis of ypt2, an essential ras-related gene in the fission yeast Schizosaccharomyces pombe encoding a Sec4 protein homologue. Haubruck, H., Engelke, U., Mertins, P., Gallwitz, D. EMBO J. (1990) [Pubmed]
  19. Mso1 is a novel component of the yeast exocytic SNARE complex. Castillo-Flores, A., Weinberger, A., Robinson, M., Gerst, J.E. J. Biol. Chem. (2005) [Pubmed]
  20. Overexpression of a dominant-negative allele of SEC4 inhibits growth and protein secretion in Candida albicans. Mao, Y., Kalb, V.F., Wong, B. J. Bacteriol. (1999) [Pubmed]
  21. Interactions of three domains distinguishing the Ras-related GTP-binding proteins Ypt1 and Sec4. Brennwald, P., Novick, P. Nature (1993) [Pubmed]
  22. Prospore membrane formation defines a developmentally regulated branch of the secretory pathway in yeast. Neiman, A.M. J. Cell Biol. (1998) [Pubmed]
  23. 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]
WikiGenes - Universities