TRAPP II complex assembly requires Trs33 or Trs65.
TRAPP is a multi-subunit complex that acts as a Ypt/Rab activator at the Golgi apparatus. TRAPP exists in two forms: TRAPP I is comprised of five essential and conserved subunits and TRAPP II contains two additional essential and conserved subunits, Trs120 and Trs130. Previously, we have shown that Trs65, a nonessential fungi-specific TRAPP subunit, plays a role in TRAPP II assembly. TRS33 encodes another nonessential but conserved TRAPP subunit whose function is not known. Here, we show that one of these two subunits, nonessential individually, is required for TRAPP II assembly. Trs33 and Trs65 share sequence, intracellular localization and interaction similarities. Specifically, Trs33 interacts genetically with both Trs120 and Trs130 and physically with Trs120. In addition, trs33 mutant cells contain lower levels of TRAPP II and exhibit aberrant localization of the Golgi Ypts. Together, our results indicate that in yeast, TRAPP II assembly is an essential process that can be accomplished by either of two related TRAPP subunits. Moreover, because humans express two Trs33 homologues, we propose that the requirement of Trs33 for TRAPP II assembly is conserved from yeast to humans.
Department of Biological Sciences, Laboratory for Molecular Biology, University of Illinois at Chicago, Molecular Biology Research Building, 900 South Ashland Avenue Chicago, IL 60607, USA.
Andrei A
AA
Tokarev
David
D
Taussig
Geetanjali
G
Sundaram
Zhanna
Z
Lipatova
Yongheng
Y
Liang
Jonathan W
JW
Mulholland
Nava
N
Segev
D000595:Amino Acid Sequence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D029701:Saccharomyces cerevisiae Proteins; C080595:TRS65 protein, S cerevisiae; C507430:Trs33 protein, S cerevisiae; D033921:Vesicular Transport Proteins