PMID- 10329739
OWN - NLM
STAT- MEDLINE
DCOM- 19990709
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 21
DP  - 1999 May 21
TI  - Vps9p is a guanine nucleotide exchange factor involved in vesicle-mediated 
      vacuolar protein transport.
PG  - 15284-91
AB  - Vacuolar protein sorting (vps) mutants of Saccharomyces cerevisiae missort and 
      secrete vacuolar hydrolases. The gene affected in one of these mutants, VPS21, 
      encodes a member of the Sec4/Ypt/Rab family of small GTPases. Rab proteins play 
      an essential role in vesicle-mediated protein transport. Using both yeast 
      two-hybrid assays and chemical cross-linking, we have identified another VPS gene 
      product, Vps9p, that preferentially interacts with a mutant form of Vps21p-S21N 
      that binds GDP but not GTP. In vitro purified Vps9p was found to stimulate GDP 
      release from Vps21p in a dose-dependent manner. Vps9p also stimulated GTP 
      association as a result of facilitated GDP release. However, Vps9p did not 
      stimulate guanine nucleotide exchange of GTP-bound Vps21p or GTP hydrolysis. We 
      tested the ability of Vps9p to stimulate the intrinsic guanine nucleotide 
      exchange activity of Rab5, which is a mammalian sequence homologue of Vps21p, and 
      Ypt7p, which is another yeast Rab protein involved in vacuolar protein transport. 
      Rab5, but not Ypt7p was responsive to Vps9p, which indicates that Vps9p 
      recognizes sequence variation among Rab proteins. We conclude that Vps9p is a 
      novel guanine nucleotide exchange factor that is specific for Vps21p/Rab5. Since 
      there are no obvious Vps9p sequence homologues in yeast, Vps9p may also possess 
      unique regulatory functions required for vacuolar protein transport.
FAU - Hama, H
AU  - Hama H
AD  - Department of Biochemistry, University of Texas Southwestern Medical Center, 
      Dallas, Texas 75235-9038, USA.
FAU - Tall, G G
AU  - Tall GG
FAU - Horazdovsky, B F
AU  - Horazdovsky BF
LA  - eng
GR  - GM-55301/GM/NIGMS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Carrier Proteins)
RN  - 0 (Fungal Proteins)
RN  - 0 (Guanine Nucleotide Exchange Factors)
RN  - 0 (Saccharomyces cerevisiae Proteins)
RN  - 0 (VPS9 protein, S cerevisiae)
RN  - 0 (Vesicular Transport Proteins)
RN  - 5Z93L87A1R (Guanine)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - EC 3.6.1.- (GTP-Binding Proteins)
RN  - EC 3.6.5.2 (rab GTP-Binding Proteins)
SB  - IM
MH  - Biological Transport
MH  - Carrier Proteins/*metabolism
MH  - Fungal Proteins/genetics/*metabolism
MH  - GTP-Binding Proteins/genetics/metabolism
MH  - Guanine/metabolism
MH  - Guanine Nucleotide Exchange Factors
MH  - Guanosine Triphosphate/metabolism
MH  - Mutation
MH  - *Saccharomyces cerevisiae Proteins
MH  - Vacuoles/*metabolism
MH  - *Vesicular Transport Proteins
MH  - *rab GTP-Binding Proteins
EDAT- 1999/05/18 00:00
MHDA- 1999/05/18 00:01
CRDT- 1999/05/18 00:00
PHST- 1999/05/18 00:00 [pubmed]
PHST- 1999/05/18 00:01 [medline]
PHST- 1999/05/18 00:00 [entrez]
AID - S0021-9258(19)73220-7 [pii]
AID - 10.1074/jbc.274.21.15284 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 May 21;274(21):15284-91. doi: 10.1074/jbc.274.21.15284.