Cytochrome c oxidase subunit Vb family signature and profile

Cytochrome c oxidase (EC 1.9.3.1) [1] is an oligomeric enzymatic complex which is a component of the respiratory chain complex and is involved in the transfer of electrons from cytochrome c to oxygen. In eukaryotes this enzyme complex is located in the mitochondrial inner membrane; in aerobic prokaryotes it is found in the plasma membrane. In addition to the three large subunits that form the catalytic center of the enzyme complex there are, in eukaryotes, a variable number of small polypeptidic subunits. One of these subunits which is known as Vb in mammals, V in slime mold and IV in yeast, binds a zinc atom. The sequence of subunit Vb is well conserved and includes three to four conserved cysteines that coordinate the zinc ion [2,3]. Two of these cysteines are clustered in the C-terminal section of the subunit; we have used this region as a signature pattern. We also developed a profile that covers the whole subunit Vb zinc binding region.