The yeast casein kinase Yck3p is palmitoylated, then sorted to the vacuolar membrane with AP-3-dependent recognition of a YXXPhi adaptin sorting signal.

Our previous work found the two yeast plasma membrane-localized casein kinases Yck1p and Yck2p to be palmitoylated on C-terminal Cys-Cys sequences by the palmitoyl transferase Akr1p. The present work examines a third casein kinase, Yck3p, which ends with the C-terminal sequence Cys-Cys-Cys-Cys-Phe-Cys-Cys-Cys. Yck3p is palmitoylated and localized to the vacuolar ...
membrane. While the C-terminal cysteines are required for this palmitoylation, Akr1p is not. Palmitoylation requires the C-terminal Yck3p residues 463-524, whereas information for vacuolar sorting maps to the 409-462 interval. Vacuolar sorting is disrupted in cis through deletion of the 409-462 sequences and in trans through mutation of the AP-3 adaptin complex; both cis- and trans-mutations result in Yck3p missorting to the plasma membrane. This missorted Yck3p restores 37 degrees C viability to yck1Delta yck2-ts cells. yck1Delta yck2-ts suppressor mutations isolated within the YCK3 gene identify the Yck3p vacuolar sorting signal-the tetrapeptide YDSI, a perfect fit to the YXXPhi adaptin-binding consensus. Although YXXPhi signals have a well-appreciated role in the adaptin-mediated sorting of mammalian cells, this is the first signal of this class to be identified in yeast.
Mesh Terms:
Acyltransferases, Casein Kinase I, Casein Kinases, Cysteine, Fungal Proteins, Mutation, Protein Kinases, Protein Structure, Tertiary, Protein Transport, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Vacuoles
Mol. Biol. Cell
Date: Mar. 01, 2004
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