How the primary sequence of a protein encodes conformational preferences that operate early in folding to promote efficient formation of the correct native topology is still poorly understood. To address this issue, we have prepared a set of yeast iso-1-cytochrome c variants that contain polyalanine inserts ranging from 6 to 30 residues in length near the N terminus of the protein. We study the...

Amino-terminal processing in the yeast Saccharomyces cerevisiae has been investigated by examining numerous mutationally altered forms of iso-l-cytochrome c. Amino-terminal residues of methionine were retained in sequences having penultimate residues of arginine, asparagine, glutamine, isoleucine, leucine, lysine, and methionine; in contrast, the amino-terminal methionine residues were exercise...

The COX6 gene encodes subunit VI of cytochrome c oxidase. Previously, this gene and its mRNAs were characterized, and its expression has been shown to be subject to glucose repression/derepression. In this study we have examined the effects of heme and the HAP1 (CYP1) and HAP2 genes on the expression of COX6. By quantitating COX6 RNA levels and assaying beta-galactosidase activity in yeast cell...

Incubation of the 125I-labeled apoprotein, prepared from 125I-labeled iso-1-cytochrome c, with a yeast mitochondrial fraction in the presence of hemin, NADPH, and an extract of the postmitochondrial fraction at 32 +/- 1 degree C for 30 min has resulted in formation of cytochrome c-like species in yields of up to 35%. This radioactive synthesized species contains a functional group which respond...