The human NADH : ubiquinone oxidoreductase NDUFS5 (15 kDa) subunit: cDNA cloning, chromosomal localization, tissue distribution and the absence of mutations in isolated complex I-deficient patients

We have cloned the cDNA of the NDUFS5 subunit (15 kDa) of the human mitocho ndrial respiratory chain complex NADH:ubiquinone oxidoreductase (complex I) . The open reading frame consists of 321 base-pairs, coding for 106 amino a cids, with a calculated molecular mass of 12.5 kDa There is an 81.0% identi ty with the bovine equivalent on cDNA level and 74.5% identity on amino aci d basis. PCR analysis of rodent-human somatic cell hybrids revealed that th e human NDUFS5 gene maps to chromosome 1. The NDUFS5 mRNA is expressed ubiq uitously in human tissues, with a relative higher expression in human heart , skeletal muscle, liver, kidney and fetal heart. A mutation detection stud y of twenty isolated enzymatic complex I-deficient patients revealed no mut ations, nor polymorphisms.