Multiple variant mRNAs with different length tandem repeats of (CAYYCC)n produced from bovine selenoprotein P-like protein gene

ABSTRACT

In contrast to selenoprotein Ps (SeIPs) from other animal species, bovine selenoprotein P-like-protein (SeIPLP) was found to contain a tandem repeat of (CAYYCC)(11). During an investigation into whether SeIPLP was a bovine substitute for SeIP or uniquely bovine, its mRNA was found to consist of multiple variants with different length tandem repeat, namely p(0) with (CAYYCC)(11), p(-4) lacking (CAYYCC)(4), p(-8) lacking (CAYYCC)(8), and p(-9) lacking (CAYYCC)(9). Although they were encoded on a single gene locus, neither classicalGT-AG: nor minor classAT-AC: donator-acceptor sequences for alternative splicing were identified. A subsequent S1 protection assay using oligonucleotides, whose sequence may occur as variants, performed against bovine poly(A)(+)RNA identified a total of nine variants. Judging from the sequence of these variants and the branch point mapping, the consensus sequence for recognition of the donator was CACCCCCAC: and of the acceptor and the branch point A nucleotide,ACCCC: CAT orACCCC: CATCCCCAT. Furthermore, when the p(0) insert mRNA was expressed in COS-7 cells derived from an African green monkey kidney, cDNAs corresponding to p(-8) and p(-9) could be isolated. Therefore, the bovine SeIPLP mRNAs consisted of multiple variants probably due to a novel splicing mechanism which was not bovine-specific but common to other mammals.