Cloning of the murine unconventional myosin gene Myo9b and identification of alternative splicing

We report the cloning of a cDNA for the mouse unconventional myosin Myo9b, the orthologue of the rat myr5 and human MYOIXb genes, A full-length spleen cDNA of 7087 bp encoding a protein of 1961 amino acids was isolated. By RT -PCR, we show that Myo9b is expressed in a wide range of tissues, including heart, brain, muscle and inner ear. In addition, we have identified two al ternatively spliced exons. Equivalent exons have not been previously report ed for either the human or rat homologues. These exons are located in the M yo9b specific actin-binding site insert of the head domain and in the tail region. A third splice form utilizing an alternative reading frame within t he 3'UTR is also described. Several polymorphisms within the coding region were identified; of interest is an in-frame 33 bp imperfect duplication wit hin the tail region that was observed only in the C57B1/6 strain. Myo9b has been previously mapped to mouse chromosome 8 and is a candidate for the mo use mutations myodystrophy and quinky. (C) 1999 Elsevier Science B.V. All r ights reserved.