Coq4p was shown to peripherally associate with the matrix face of the mitochondrial inner membrane. The putative mitochondrial- targeting sequence present at the amino-terminus of the polypeptide efficiently imported it to mitochondria. The function of Coq4p is unknown, although its presence is required to maintain a steady-state level of Coq7p, another component of the Q biosynthetic pathway [1]. The overall structure of Coq4 is alpha helical and shows resemblance to haemoglobin/myoglobin (information from TOPSAN).

1: Yeast COQ4 encodes a mitochondrial protein required for coenzyme Q synthesis. Belogrudov GI, Lee PT, Jonassen T, Hsu AY, Gin P, Clarke CF; Arch Biochem Biophys 2001;392:48-58. PMID:11469793