The primary structure of cytochrome c1 from Neurospora crassa

The primary structure of the cytochrome c1 subunit of ubiquinol-cytochrome-c reductase from mitochondria of Neurospora crassa was determined by sequencing the cDNA of a bank cloned in Escherichia coli. From the coding region the sequence of 332 amino acids, corresponding to the molecular mass of 36,496 Da, was derived for the precursor protein. The mature protein, the N terminus of which was previously sequenced [Tsugita et al. (1979) in Cytochrome oxidase (King, T. E. et al., eds) pp. 67-77, Elsevier, New York], consists of 262 amino acids and has the molecular mass of 29,908 Da including the heme. The sequence contains an N-terminal hydrophilic part of 211 residues, which carries the heme, a hydrophobic stretch of 15 residues, which is assumed to anchor the protein to the membrane, and a C-terminal hydrophilic part of 36 residues. The N-terminal presequence of 70 amino acids contains 9 positive charges but only 1 negative charge and is characterized by a stretch of 20 uncharged residues.