Alternative titles; symbols
HGNC Approved Gene Symbol: MYH7B
Cytogenetic location: 20q11.22 Genomic coordinates (GRCh38): 20:34,955,868-35,002,437 (from NCBI)
By sequencing clones obtained from a size-fractionated fetal brain cDNA library, Nagase et al. (2000) cloned MYH7B, which they designated KIAA1512. The deduced 1,692-amino acid protein shares 71% identity with MYH7 (160760). RT-PCR ELISA detected high MYH7B expression in heart, skeletal muscle, testis, adult and fetal brain, and all specific adult brain regions examined. Slightly lower expression was detected in ovary and kidney, and intermediate expression was detected in lung, pancreas, spleen, and adult and fetal liver.
By screening genomic cosmid libraries for myosin heavy chain genes, followed by cDNA hybridization and PCR amplification, Desjardins et al. (2002) cloned MYH7B, which they called MYH14. The deduced protein contains several class II myosin consensus sequences and has a tail region of about 1,100 amino acids with homology to both class II myosins and dimerization domains of leucine zipper proteins. In its N-terminal catalytic domain, MYH14 has novel surface loop sequences, including substitutions in the aliphatic sequence of loop 1 and paired prolines in loop 2. Desjardins et al. (2002) compared the motor domain of MYH14 with those of other MYHs and concluded that MYH14 is a slow-twitch myosin. Database analysis identified MYH14 ESTs in libraries obtained from whole embryo, pooled human tissue cDNA, and well-differentiated endometrial adenocarcinoma.
By scanning mouse myosin genes for intronic microRNAs (miRNAs), van Rooij et al. (2009) identified Mir499 (613614) within intron 19 of the Myh7b gene. Northern blot analysis showed that Mir499 and Myh7b were highly expressed in mouse heart and the slow-twitch soleus muscle, but not in the fast-twitch gastrocnemius/plantaris, tibialis anterior, and extensor digitorum longus muscles.
Desjardins et al. (2002) determined that the MYH7B gene contains at least 40 coding exons and spans about 24 kb.
Van Rooij et al. (2009) identified an miRNA, Mir499 (613614), within intron 19 of the mouse Myh7b gene.
By radiation hybrid analysis, Nagase et al. (2000) mapped the MYH7B gene to chromosome 20. Desjardins et al. (2002) confirmed this localization by genomic sequence analysis.
Van Rooij et al. (2009) found that expression of Myh7b and its intronically encoded miRNA, Mir499, was upregulated in mouse heart by hypothyroidism caused by inhibition of triiodothyronine (T3; see 188450) synthesis. This upregulation was reversed by T3 administration. Gain- and loss-of-function experiments in mice showed that expression of Myh7b and Mir499 was controlled by the dominant miRNA in mouse heart, Mir208a (611116).
Desjardins, P. R., Burkman, J. M., Shrager, J. B., Allmond, L. A., Stedman, H. H. Evolutionary implications of three novel members of the human sarcomeric myosin heavy chain gene family. Molec. Biol. Evol. 19: 375-393, 2002. [PubMed: 11919279] [Full Text: https://doi.org/10.1093/oxfordjournals.molbev.a004093]
Nagase, T., Kikuno, R., Ishikawa, K., Hirosawa, M., Ohara, O. Prediction of the coding sequences of unidentified human genes. XVII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro. DNA Res. 7: 143-150, 2000. [PubMed: 10819331] [Full Text: https://doi.org/10.1093/dnares/7.2.143]
van Rooij, E., Quiat, D., Johnson, B. A., Sutherland, L. B., Qi, X., Richardson, J. A., Kelm, R. J., Jr., Olson, E. N. A family of microRNAs encoded by myosin genes governs myosin expression and muscle performance. Dev. Cell 17: 662-673, 2009. [PubMed: 19922871] [Full Text: https://doi.org/10.1016/j.devcel.2009.10.013]