Plasma membrane multidrug efflux pump that confers resistance to numerous chemicals including azoles such as fluconazole, voriconazole, and benztriazoles, as well as to benomyl, cycloheximide, methotrexate, 4-nitroquinoline-N-oxide, sulfometuron methyl, cerulenin, and brefeldin A. Constitutive, high-level transcription is commonly observed in laboratory and clinical strains of Candida albicans that are resistant to the antifungal drug fluconazole. Multiple cis-acting sequences within the promoter mediate its activation. One, a benomyl response element (BRE), is situated at position -296 to -260. It is required for benomyl-dependent MDR1 up-regulation and is also necessary for constitutive high expression of MDR1. A second element, termed H(2)O(2) response element (HRE), is situated at position -561 to -520. The HRE is required for H(2)O(2)-dependent MDR1 up-regulation, but dispensable for constitutive high expression. Two potential binding sites (TTAG/CTAA) for the transcription factor CAP1 lie within the HRE. Expression is induced by fluconazole, rifampicin, methotrexate, diethylmaleate, diamide, 4-nitroquinoline-N-oxide, benomyl, o-phenanthroline (OP), hydrogen peroxide, methyl methanesulfonate, and sulfometuron methyl. Expression is down-regulated by tetrandrine and levofloxacin derivatives. Transcription is positively regulated by ADA2, CAP1, MRR1, UPC2, and TAC1; and negatively regulated by REP1. Transcription is also regulated by the general transcription factor MCM1. MCM1 is dispensable for up-regulation by H(2)O(2) but is required for full induction by benomyl. The central cytoplasmic loop (residues 295 to 350) is critical for the function, but unlike other homologous proteins, has no apparent role in imparting substrate specificity or in the recruitment of the transporter protein. Leads to enhanced susceptibility against fluconazole, methotrexate, 4-nitroquinoline-N-oxide, and cycloheximide. The overexpression of MDR1 is a frequent cause of resistance to the widely used antimycotic agent fluconazole and other toxic compounds in the pathogenic yeast Candida albicans. Belongs to the major facilitator superfamily. CAR1 family.