cDNA cloning of two splice variants of a human copper-containing monoamine oxidase pseudogene containing a dimeric Alu repeat sequence

Two alternatively spliced transcripts, psi HLAO1 and psi HLAO2, of a copper-containing monoamine oxidase pseudogene have been isolated from a human-liver cDNA library. The larger psi HLAO1 cDNA (2073 bp) contains a 5'-flanking segment of 134 bp, followed by an apparent open reading frame (ORF) of 1725 bp. The deduced amino acid sequence of this ORF (574 residues) shares 81.0% similarity with the 763-residue monoamine oxidase from human placenta (HPAO) (the N-terminal 533 residues of psi HLAO1 share 86.7% similarity with HPAO). The psi HLAO1 ORF is interrupted by an in-frame stop codon corresponding to amino acid 225 and terminates within a type S(a) dimeric Alu repeat sequence. psi HLAO2 appears to be an alternatively spliced variant of psi HLAO1 that has 413 bases of psi HLAO1 excised according to the 'GT-AG' rule. The slightly longer 3' end of the psi HLAO2 transcript shows that the Alu repeat is followed by an Il-bp poly(A) tract that, in turn, is followed by an AT-rich (81%) sequence of 105 bp. A reverse transcriptase-polymerase chain reaction (RT-PCR) protocol was used to confirm that both psi HLAO1 and psi HLAO2 are transcribed in human liver and placenta. A search of the expressed sequence tag (EST) database indicates that, like HPAO, psi HLAO derives also from the region 17q21 of the human genome. (C) 1998 Elsevier Science B.V. All rights reserved.