Pneumocystis carinii dihydrofolate reductase ternary complex with NADPH and the inhibitor 24, (N~6~-METHYL-N~6~-(NAPHTHALEN-1-YL)PYRIDO[2,3-D]PYRIMIDINE-2,4,6-TRIAMINE)
[DYR_PNECA] Key enzyme in folate metabolism. Catalyzes an essential reaction for de novo glycine and purine synthesis, and for DNA precursor synthesis.