FIG 5.

Phosphorylation pattern of proteins in the Ras1-Cyr1-PKA pathway in C. albicans. (A) Schematic model and the phosphorylation states of the Ras1-Cyr1-PKA pathway in C. albicans. Ras1 activity is governed by Ira2 and Cdc25, which both contain P sites. Ras1 induces adenylate cyclase (Cyr1) to produce cAMP, which inhibits the formation of the protein kinase A complex consisting of the catalytic subunits Tpk1 and -2, and the regulatory subunit Bcy1, by directly binding to Bcy1. Phosphorylation states are depicted by color (open ovals, no phosphorylation; green ovals, <3 P sites; orange ovals, between 4 and 10 P sites; and red jagged ovals, >10 P sites). (B) An alignment of ScBcy1 and CaBcy1 shows high overall similarity. S. cerevisiae Ser145 is within an RRxS/T motif which is recognized by PKA (red box); this serine corresponds to Ser180 in C. albicans. The blue arrows indicate the Bcy1 P sites (Q9HEW1; see Table S3 in the supplemental material).