High impact information on SPH1

• SPH1, which is similar to SPA2, is required for bipolar budding and plays a role in shmoo formation [1].
• Searching the yeast genome database revealed a previously uncharacterized protein which we name, Sph1p (a2p omolog), with significant homology to the localization domain and amino terminus of Spa2p [1].
• Sph1p interacts in the two-hybrid system with three mitogen-activated protein (MAP) kinase kinases (MAPKKs): Mkk1p and Mkk2p, which function in the cell wall integrity/cell polarization MAP kinase pathway, and Ste7p, which operates in the pheromone and pseudohyphal signaling response pathways [2].
• We speculate that Spa2p and Sph1p may function during pseudohyphal and haploid invasive growth to help tether this MAP kinase module to sites of polarized growth [2].
• Our results indicate that Spa2p and Sph1p comprise two related proteins important for the control of cell morphogenesis in yeast [2].

Biological context of SPH1

• In vivo targets of Hub1 conjugation included cell polarity factors Sph1 and Hbt1 [3].

Associations of SPH1 with chemical compounds

• In the present study, supplying SPH (sphingosine), an unnatural LCB for yeast, similarly rescued the Deltalcb2 cells, but only when SPH 1-phosphate production was inhibited by deleting the LCB kinase gene LCB4 [4].

Other interactions of SPH1

• The Spa2-related protein, Sph1p, is important for polarized growth in yeast [2].
• Consistent with a role in polarized growth, Sph1p localizes to growth sites in a cell cycle-dependent manner: Sph1p concentrates as a cortical patch at the presumptive bud site in unbudded cells, at the tip of small, medium and large buds, and at the bud neck prior to cytokinesis [2].
• In the hub1Delta mutant, the subcellular localization of both Hbt1 and Sph1 was disrupted, and cell polarization during the formation of mating projections was defective [3].

References