Organization of the mouse microfibril-associated glycoprotein-2 (MAGP-2) gene

Abstract

A 1.4-kb EST clone encoding mouse microfibril-associated glycoprotein-2 (MAGP-2), identified by its similarity with the reported human cDNA, was used to screen a mouse 129 genomic bacterial artificial chromosome (BAC) library. The mouse gene contains 10 exons spanning 16 kb, located on the distal region of Chromosome (Chr) 6. The exons range in size from 24 to 963 bp, with the ATG located in exon 2. The tenth and largest exon contains 817 bp of 3' untranslated sequence, including a B2 repetitive element. Northern analysis demonstrates abundant expression of MAGP-2 mRNA in skeletal muscle, lung, and heart. Sequence analysis of additional cDNA clones suggests that the two mRNA forms of MAGP-2 in the mouse arise from alternative polyadenylation site usage. The promoter does not contain an obvious TATA box, and the sequence surrounding the start site does not conform to the consensus for an initiator promoter element. Additionally, the mouse promoter contains 22 copies of a CT dinucleotide repeat sequence located approximately 155 bp 5' to exon 1. MAGP-2 gene and compared it with that of the human gene (Hatzinikolas and Gibson 1998). While the mouse and human MAGP-2 proteins are similar in sequence, the promoters for the two genes share little in common. The presence of two mRNA species for MAGP-2 in the mouse raised the possibility that more than one isoform of the protein might be synthesized. We have characterized both mRNA species and determined that they do not code for different variants of the protein.