Figure 1. Amino acid sequence alignment of full length mouse Myo3B (mMyo3B) with mouse Myo3A (mMyo3A) (Clustal X, Young, 1976) showing regions of particular interest for this study.

The amino acid numbering for each sequence is indicated at the right; black boxes indicate amino acids that are conserved between the two sequences. The kinase, myosin motor and tail domains are labeled and were predicted using the InterProScan program from EMBL-EBI. The loop2 actin binding region within the myosin domain and Mouse 3 tail homology domain I (3THDI) are indicated with dashed horizontal lines. The loop2 region was predicted from an alignment with chicken skeletal muscle myosin (Accession # P13538, Sellers, 1999). 3THDI was identified by Dosé et al. (2003) and is a region within the tail domains of class III myoisns that has relatively high amino acid identity among sequences. Sequences N-terminal to the vertical dashed line near the beginning of the motor domain include the kinase domain and most of the transition region between the kinase and myosin domains. These sequences were expressed in sf9 cells, served as the source of kinase activity and were tested as substrates for autophosphorylation. The sequences of mMyo3B below the colored solid lines were expressed in E. coli. and were tested as substrates for phosphorylation by the mMyo3 kinase domain. The sequence below the blue line includes the kinase activation region, that below the orange line includes the loop2 region and that below the green line includes THDI.. Red solid arrow heads indicate sites identified in this study that are phosphorylated by mMyo3 kinase; red open arrows indicate potential phosphorylation sites that could not be distinguished unambiguously from MS/MS fragment ions. Genbank Accession numbers: mMyo3A, AY10136; mMyo3B, NM_177376.