High impact information on YCK3

• Intriguingly, Yck3 mediates phosphorylation of the HOPS subunit Vps41, a bi-functional protein involved in both budding and fusion during vacuole biogenesis [1].
• Because Yck3 also promotes efficient vacuole inheritance, we propose that tethering complex phosphorylation is a part of a general, switch-like mechanism for driving changes in organelle architecture [1].
• The vacuolar kinase Yck3 maintains organelle fragmentation by regulating the HOPS tethering complex [1].
• Morphological and functional studies show that Yck3 modulates the Rab/homotypic fusion and vacuole protein sorting complex (HOPS)-dependent tethering stage of vacuole fusion [1].
• We report here that maintenance of the fragmented phenotype requires the vacuolar casein kinase I Yck3: when Yck3 is absent, salt-stressed vacuoles undergo fission, but reassemble in a SNARE-dependent manner, suggesting that vacuole fusion is disregulated [1].

Biological context of YCK3

• Prenylated isoforms of yeast casein kinase I, including the novel Yck3p, suppress the gcs1 blockage of cell proliferation from stationary phase [2].
• 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 [3].

Anatomical context of YCK3

• Some Yck3p gene product was found associated with the plasma membrane, like Yck1p and Yck2p, but most confractionated with the nucleus, like another yeast casein kinase I isoform, Hrr25p [2].

Associations of YCK3 with chemical compounds

• On the other hand, CKI-3 accepts both ATP and GTP with equal efficiency, and it is heparin sensitive (50% inhibition at 0.3 microgram/mL) like type II casein kinases [4].
• CKI-3 differs from the other three yeast casein kinases in requiring a low pH (5.5) and a high MgCl2 concentration (50 mM) for optimal activity [4].

Other interactions of YCK3

• Only one of the enzymes (CKII) was retained by DEAE-cellulose, whereas the three other enzymes (CKI-1, CKI-2, and CKI-3) were absorbed to CM-Sephadex, eluted with 250 and 600 mM NaCl, and fractionated by heparin-Sepharose chromatography [4].

Analytical, diagnostic and therapeutic context of YCK3

• The casein kinase CKI-3 eluting at the highest NaCl concentration (550 mM) was purified to electrophoretic homogeneity by fast protein liquid chromatography [4].

References