| Modification Notes |
Phosphatidylinositol 4-kinases are molecules that function as important second messengers in various cellular processes. Pik1 is a 1066 amino acid phosphatidylinositol 4-kinase present in yeast that localizes to the cytoplasmic puncta and the nucleus. Pik1 catalyzes the first committed step in the pathway that produces the second messenger inositol-1,4,5-trisphosphate, which is used during signal transduction. Pik1 is necessary for normal cellular secretion, Golgi and vacuole membrane dynamics, as well as endocytosis. Pik1 may also control cytokinesis via the actin cytoskeleton. Frequenin (Frq1), a 190-residue N-myristoylated calcium-binding protein, associates tightly with the N terminus of Pik1, and both are essential for viability and growth. |