Suppressors of YCK-encoded yeast casein kinase 1 deficiency define the four subunits of a novel clathrin AP-like complex.
In Saccharomyces cerevisiae, the redundant YCK1 and YCK2 genes (Yeast Casein Kinase 1) are required for viability. We describe here the molecular analysis of four mutations that eliminate the requirement for Yck activity. These mutations alter proteins that resemble the four subunits of clathrin adaptors (APs), with highest sequence similarity to those of the recently identified AP-3 complex. The four yeast subunits are associated in a high-molecular-weight complex. These proteins have no essential function and are not redundant for function with other yeast AP-related proteins. Combination of suppressor mutations with a clathrin heavy chain mutation (chc1-ts) confers no synthetic growth defects. However, a yck(ts) mutation shows a strong synthetic growth defect with chc1-ts. Moreover, endocytosis of Ste3p is dramatically decreased in yck(ts) cells and is partially restored by the AP suppressor mutations. These results suggest that vesicle trafficking at the plasma membrane requires the activity of Yck protein kinases, and that the new AP-related complex may participate in this process.
Panek
H R
HR
LSU Medical Center, Department of Biochemistry and Molecular Biology, Shreveport, LA 71130, USA.
Stepp
J D
JD
Engle
H M
HM
Marks
K M
KM
Tan
P K
PK
Lemmon
S K
SK
Robinson
L C
LC
D033942:Adaptor Proteins, Vesicular Transport; D015153:Blotting, Western; D047389:Casein Kinase I; D047388:Casein Kinases; D002455:Cell Division; D002966:Clathrin / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D034041:Monomeric Clathrin Assembly Proteins; D009024:Morphogenesis; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic / Q000235:genetics*
D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; D008565:Membrane Proteins; D034041:Monomeric Clathrin Assembly Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D051964:Receptors, Mating Factor; D043563:Receptors, Pheromone; C081863:STE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C439023:clathrin assembly protein AP180; D011494:Protein Kinases; D047389:Casein Kinase I; D047388:Casein Kinases; C479664:YCK1 protein, S cerevisiae; C479666:YCK2 protein, S cerevisiae