EXTENSION OF THE MITOCHONDRIAL TRANSPORTER SUPER-FAMILY - SEQUENCES OF 5 MEMBERS FROM THE NEMATODE WORM, CAENORHABDITIS-ELEGANS

The sequences are presented of cDNAs encoding five related proteins fr om the nematode worm, Caenorhabditis elegans. Three of them can be rec ognised as the homologues of the ADP/ATP, phosphate and oxoglutarate/m alate carrier proteins that have been found in the inner membranes of mitochondria in other species. These carrier proteins, and the uncoupl ing protein from the mitochondria in mammalian brown adipose tissue, h ave common features in their primary and secondary structures, and are members of the same protein super-family. Members of this super-famil y have polypeptide chains approximately 300 amino acid long that consi st of three tandem related sequences of about 100 amino acids. The tan dem repeats from the different proteins are inter-related, and each re peat is probably folded into a common secondary structural motif consi sting of two hydrophobic stretches of amino acids with the potential t o form membrane spanning alpha-helices, linked by an extensive hydroph ilic region. The common characteristic features of this family of prot eins are also present in sequences of two further proteins, named C1 a nd C2, encoded in nematode cDNAs, and in tour published protein sequen ces from various sources. Neither the transport properties nor the sub cellular locations of any of this latter group of six proteins are kno wn. Therefore, currently the super-family of mitochondrial carrier pro teins has at least ten different members.