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Updated: Aug 10, 2026

Growth-based Determination and Biochemical Confirmation of Genetic Requirements for Protein Degradation in Saccharomyces cerevisiae
Published on: February 16, 2015
Cellular localization and phosphorylation of Hrb1p is independent of Sky1p
Ziv Porat1, Omri Erez, Chaim Kahana
1Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, ISRAEL.
Abstract:
Protein phosphorylation plays a major role in regulating cellular functions. We have previously demonstrated that Sky1p, the SR protein kinase of the budding yeast Saccharomyces cerevisiae, is a regulator of polyamine transport and ion homeostasis. Since its kinase activity was demonstrated essential for fulfilling these roles, we assumed that Sky1p function via substrates phosphorylation. Using an in vitro phosphorylation assay, we have identified Hrb1p as a putative Sky1p substrate. However, phosphorylation analysis in WT and sky1Delta cells and localization studies disproved Hrb1p as a true Sky1p substrate, although a segment of the RS domain is required for determining its subcellular localization. Furthermore, we demonstrate that Hrb1p and additional putative Sky1p substrates, identified by computational approach, are not involved in mediating the spermine tolerant phenotype of sky1Delta cells.
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