Cholesterol inhibitor produced by Monascus, monacolin k, is a secondary metabolite of polyketides. The invention provides probes specific to monacolin k biosynthesis gene cluster. BAC clones having putative monacolin k gene cluster were screened from BAC (bacterial artificial chromosome) library, and sequencing and annotation were performed on these clones. The results show that 2 polyketide synthase (PKS) genes and 7 regulatory genes related to monacolin k synthesis were obtained. Full-length cDNAs of these genes were then obtained by RT-PCR and cloned to expression vectors for the expression of these genes.