Cloning and mRNA expression of human unconventional myosin-IC. A homologue of amoeboid myosins-I with a single IQ motif and an SH3 domain

J Mol Biol. 1994 Oct 21;243(2):356-63. doi: 10.1006/jmbi.1994.1662.


The complete deduced amino acid sequence and mRNA expression of human unconventional myosin-IC (HuncM-IC) are described. Sequencing of overlapping cDNA clones reveals a message of 4666 nucleotides with a single open reading frame predicted to encode a 127 kDa protein of 1109 amino acids. HuncM-IC is composed of three discrete regions: a characteristic N-terminal myosin head with predicted actin and ATP-binding sites; a neck domain with an "IQ motif", predicted to bind a single light chain; and a C-terminal tail with a putative membrane-binding site. In addition, the tail contains an src-homology 3 domain. The presence of a single IQ motif and an src-homology 3 domain is reminiscent of "long-tailed" myosins-I from amoeboid organisms, a supposition confirmed by multiple sequence alignment. Northern blot analysis of human tissues shows that HuncM-IC is ubiquitously expressed, with the highest levels in kidney, prostate, colon, liver and ovary. The results show that "amoeboid" myosins-I are not restricted to amoeboid organisms, rather they are expressed in the metazoa as well.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acanthamoeba / chemistry
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cloning, Molecular
  • Dictyostelium / chemistry
  • Humans
  • Molecular Sequence Data
  • Myosins / chemistry*
  • Myosins / genetics
  • RNA, Messenger / biosynthesis
  • Sequence Homology, Amino Acid


  • RNA, Messenger
  • Myosins

Associated data

  • GENBANK/U14391