Ste50

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About Ste50

ste50Δ strains are partially defective in mating response as measured by transcription, mating efficiency, and cell cycle arrest. Wu et al. 1999 PMID 10397774

Ste50 has a SAM (Sterile Alpha Motif) domain at residues 32-101, which is required for its interaction with Ste11. Jansen et al. 2001 PMID 11370856

Overexpression of Ste50 results in hyper-sensitivity to pheromone. Ramezani-Rad. 2003 PMID 12764668

Ste50 Ras-Associating Domain (RAD) at residues 235-327 is required for proper mating signaling. Ramezani-Rad. 2003 PMID 12764668
- RAD domain is responsible for Ste50's interactions with Ras1, Ras2 and Cdc42 (unpublished results). Ramezani-Rad. 2003 PMID 12764668

Ste50 is phosphorylated in response to pheromone treatment (unpublished results). Ramezani-Rad. 2003 PMID 12764668

Ste50 phosphorylation is largely unaffected by treatment with 5 μM pheromone (as judged by autoradiography of 2D gel of ³²P-labeled tryptic digest). Wu et al. 2003 PMID 14555477

Overexpression of Ste50 is able to partially compensate for deletion of Ste20 (mating assay). Wu et al. 2003 PMID 14555477

Phosphorylation of T42 in the Ste50 SAM domain is important for Ste50 function. Wu et al. 2003 PMID 14555477
- Out of the 9 serines and threonines in the Ste50 SAM domains, only mutation of T42 to alanine impared Ste50's ability to compensate for deletion of Ste20 (30-fold lower mating efficiency than WT Ste50).

T42 of Ste50 is phosphorylated by Yck1 and Yck2. Wu et al. 2003 PMID 14555477
- T42 fits the canonical CKI family (of which the Yck proteins are members) target consensus sequence.
- T42 (along with other residues in the first 67 amino acids) were phosphorylated by Yck1, Yck2 and Hrr25 in vitro.
- T42 is phosphorylated in vivo (comparison of T42 and T42A by autoradiography of 2D gel of ³²P-labeled triptic digest).

WT Ste50 cosediments both in light fractions, as well as in heavy fractions that contain Fus3 and Ste5. Pheromone treatment increases the amount of Ste50 that is found in heavy fractions. The Ste50(T42A) is only found in light fractions both in the presence and absence of pheromone. Wu et al. 2003 PMID 14555477

Ste50 is required for invasive and filamentous growth. Ramezani-Rad et al. 1998 PMID 9738877

Overexpressed Myc-Ste50 does not copurify with overexpressed GFP-Ste50. Ramezani-Rad et al. 1998 PMID 9738877

Ste50 failed to interact with itself via yeast two-hybrid in a diploid (using Gal4's activating domain and Gal4's DNA-binding domain). Kwan et al. 2004 PMID 15327964

The Ras association (RA) domain of Ste50 (residues 219-346) associates with Cdc42-GTP and Cdc42-GDP equally. The RA domain does not bind Ras2. Truckses et al. 2006 PMID 16428446
- The association between Ste50's RA domain and Cdc42 is required for proper membrane localization of Ste50 and Ste11, and is required for invasive growth and response to osmotic stress.
- The RA domain can be replaced with a membrane localization C terminal sequence (which gets prenylated) and still functions adequately in agar invasion and pseudohyphal growth, demonstrating that the main function of the RA domain in membrane localization.
- The authors imply that the RA domain is dispensable for mating response, but don't show any evidence or reference any sources.

Ste50 and Ste20 bind to different regions on Cdc42, suggesting that a single Cdc42 might be able to simultaneously bind to Ste50 and Ste20. Tatebayashi et al. 2006 PMID 16778768

Note that Ste50 is not currently included in the mode.

Ste50(Ste11_site)

Ste50(Ste11_site) Ste50_tot_conc