title: Plasma membrane localization of the Yck2p yeast casein kinase 1 isoform requires the C-terminal extension and secretory pathway function.
abstract: The S. cerevisiae Yck2 protein is a plasma membrane-associated member of the casein kinase 1 protein kinase family that, with its homolog Yck1p, is required for bud morphogenesis, cytokinesis, endocytosis and other cellular processes. Membrane localization of Yckp is critical for its function, since soluble mutants do not provide sufficient biological activity to sustain normal growth. Yck2p has neither a predicted signal sequence nor obvious transmembrane domain to achieve its plasma membrane localization, but has a C-terminal -Cys-Cys sequence that is likely to be palmitoylated. We demonstrate here that Yck2p is targeted through association with vesicular intermediates of the classical secretory pathway. Yck2p lacking C-terminal Cys residues fails to associate with any membrane, whereas substitution of these residues with a farnesyl transferase signal sequence allows sec-dependent plasma membrane targeting and biological function, suggesting that modification is required for interaction with early secretory membranes but that targeting does not require a particular modification. Deletion analysis within the 185 residue C-terminus indicates that the final 28 residues are critical for membrane association, and additional sequences just upstream are required for proper plasma membrane targeting.
authors.affiliation: Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA.
authors.forename: Praveen
authors.initials: P
authors.lastname: Babu
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Bryan
authors.forename: Heather R
authors.initials: HR
authors.lastname: Panek
authors.forename: Solomon L
authors.initials: SL
authors.lastname: Jordan
authors.forename: Brynn M
authors.initials: BM
authors.lastname: Forbrich
authors.forename: Shannon C
authors.initials: SC
authors.lastname: Kelley
authors.forename: Richard T
authors.initials: RT
authors.lastname: Colvin
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Robinson
mesh_terms: D000483:Alleles; D001483:Base Sequence; D047389:Casein Kinase I; D047388:Casein Kinases; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D049452:Green Fluorescent Proteins; D007527:Isoenzymes / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D010957:Plasmids; D011494:Protein Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D017931:DNA Primers; D007527:Isoenzymes; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D011494:Protein Kinases; D047389:Casein Kinase I; D047388:Casein Kinases; C479666:YCK2 protein, S cerevisiae