Cloning and genomic mapping of the mouse matrin 3 gene and its pseudogenes

Matrin 3 forms a family of nuclear proteins together with NP220s. Using cDNA sequences encoding rat matrin 3 as a probe, we isolated genomic clones of mouse matrin 3 gene and its two pseudogenes. The genuine mouse matrin 3 gene has an exon covering the N-terminal one third of matrin 3 with a sequence 99% identical to rat matrin 3 cDNA. The gene was localized to Chromosome 18C by in situ hybridization and mapped at 3.6 cM distal to D18Mit117 and 2.2 cM proximal to D18Mit14 on mouse Chromosome 18 by interspecific backcross analysis. One pseudogene has an exon-like sequence covering the N-terminal half of matrin 3 that is interrupted by an unknown sequence. Reverse transcription polymerase chain reaction (RT-PCR) of RNA from mouse liver and brain using unique sequences of the genuine gene and the pseudogene confirmed the expression of only the former. The other pseudogene has a sequence only 80% identical to rat cDNA and is partially deleted and reversed. These pseudogenes were localized to Chromosome 4E2 and 8D2, respectively.