The gene for human pancreatic cholesterol esterase consists of 11 exons and 10 introns and is 9.2 kb in length. The last and longest exon (841 nucleotides) is unique to the human gene. Functional amino acids are encoded on separate exons. The leader sequence is encoded by a single exon which carries two additional N-terminal amino acids of the mature functional protein. A positive TATA element is identified 43 nucleotides from the start codon. Pulse-field gel electrophoresis and hybridization with various cDNA probes and direct sequence data revealed the existence of a CEase-like gene. Partial sequence analysis of this gene from a human cosmid library and human genomic DNA showed a premature stop signal in exon 10, shortly after the codon for the active-site histidine. Both the functional gene and the CEase-like gene have a polyadenylation signal in the 3'-untranslated region. Thus, the complex gene structure for this intestinally active enzyme may provide in part a potential molecular explanation for the well-known heterogeneity of the intestinal absorption of cholesterol.

The three ribonucleic acid (RNA) polymerases (ribonucleoside triphosphate RNA nucleotidyltransferases, EC 2.7.7.6) of the two phases (yeast and mycelial) of the dimorphic fungus Histoplasma capsulatum have been purified and characterized. The corresponding enzymes from the two phases differ in sensitivity to alpha-amanitin, ion and salt requirements, temperature sensitivity, and subunit structure. This is the first case in which such qualitative differences in RNA polymerases have been demonstrated in two growth states of the same organism.