The introns of animal nuclear genes and of viral genes encoding protein possess at their 3\' splice-site the
consensus sequence (CT)11NTCAG (Mount, S.M. (1982) Nucl. Acids Res. 10, 459-472; Green, M.R. (1986) Ann. Rev. Genet. 20, 671-708). However, the total 39 introns of the 5 imported mitochondrial proteins of higher eucaryotes whose gene structure has been determined to date show a predominance of 44% for base T at position -4. Apparently, a variant
consensus sequence, i.e. (CT)11TTCAG, characterizes the genes of nuclear encoded mitochondrial proteins.