J. Hasek et al., Rpg1p, the subunit of the Saccharomyces cerevisiae eIF3 core complex, is amicrotubule-interacting protein, CELL MOTIL, 45(3), 2000, pp. 235-246
The essential gene RPG1/TIF32 of Saccharomyces cerevisiae encodes the 110-k
Da subunit of the translation initiation factor 3 (eIF3) core complex. In t
his study, the Rpg1p-specific monoclonal antibody PK1/1 was used to analyse
the cellular distribution of Rpg1p by epifluorescence and confocal laser s
canning microscopy (CLSM). In budded cells, a portion of Rpg1p was obviousl
y co-localised with microtubules. In addition, CLSM revealed an accumulatio
n of Rpg1p in a patch at the very end of cytoplasmic microtubules reaching
the bud tip. A punctate fluorescence pattern was typical for separated unbu
dded cells. Distribution of Rpg1p was confirmed using a strain expressing e
xclusively a hemaglutinin-tagged version of Rpg1p. In nocodazole-treated ce
lls, the pattern of the PK1/1 staining was disturbed. No staining was obser
ved in Rpg1p-depleted cells. In vitro experiments revealed that Rpg1p was s
pecifically co-immunoprecipitated with alpha-tubulin from the yeast cell fr
ee extract and this observation was further supported by showing that Rpg1p
co-sedimented with hog brain microtubules. We conclude that Rpg1p is a mic
rotubule-interacting protein that indicates an interesting connection betwe
en the translation initiation machinery and cytoskeleton in yeast Saccharom
yces cerevisiae. (C) 2000 Wiley-Liss, Inc.