Details

Autor(en) / Beteiligte

• Golomb, Eliahu
• Ma, Xuefei
• Jana, Siddhartha S.
• Preston, Yvette A.
• Kawamoto, Sachiyo
• Shoham, Nitza G.
• Goldin, Ehud
• Conti, Mary Anne
• Sellers, James R.
• Adelstein, Robert S.

Titel

Identification and Characterization of Nonmuscle Myosin II-C, a New Member of the Myosin II Family

Ist Teil von

• The Journal of biological chemistry, 2004-01, Vol.279 (4), p.2800-2808

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2004

Quelle

MEDLINE

Beschreibungen/Notizen

• A previously unrecognized nonmuscle myosin II heavy chain (NMHC II), which constitutes a distinct branch of the nonmuscle/smooth muscle myosin II family, has recently been revealed in genome data bases. We characterized the biochemical properties and expression patterns of this myosin. Using nucleotide probes and affinity-purified antibodies, we found that the distribution of NMHC II-C mRNA and protein (MYH14) is widespread in human and mouse organs but is quantitatively and qualitatively distinct from NMHC II-A and II-B. In contrast to NMHC II-A and II-B, the mRNA level in human fetal tissues is substantially lower than in adult tissues. Immunofluorescence microscopy showed distinct patterns of expression for all three NMHC isoforms. NMHC II-C contains an alternatively spliced exon of 24 nucleotides in loop I at a location analogous to where a spliced exon appears in NMHC II-B and in the smooth muscle myosin heavy chain. However, unlike neuron-specific expression of the NMHC II-B insert, the NMHC II-C inserted isoform has widespread tissue distribution. Baculovirus expression of noninserted and inserted NMHC II-C heavy meromyosin (HMM II-C/HMM II-C1) resulted in significant quantities of expressed protein (mg of protein) for HMM II-C1 but not for HMM II-C. Functional characterization of HMM II-C1 by actin-activated MgATPase activity demonstrated a Vmax of 0.55 + 0.18 s–1, which was half-maximally activated at an actin concentration of 16.5 + 7.2 μm. HMM II-C1 translocated actin filaments at a rate of 0.05 + 0.011 μm/s in the absence of tropomyosin and at 0.072 + 0.019 μm/s in the presence of tropomyosin in an in vitro motility assay.