Heavy chain of Acanthamoeba myosine IB is a fusion of myosin-like and non-myosin-like sequences
Acanthamoeba castellanii myosins IA and IB demonstrate the catalytic properties of a myosin and can support analogues of contractile and motile activity in vitro, but their single, low molecular weight heavy chains, roughly globular shapes, and inabilities to self-assemble into filaments make them structurally atypical myosins. The authors present the complete amino acid sequence of the 128-kDa myosin IB heavy chain, which they deduced from the nucleotide sequence of the gene and which reveals that the polypeptide is a fusion of myosin-like and non-myosin-like sequences. Specifically, the amino-terminal approx. 76 kDa of amino acid sequence is highly similar to the globular head sequences of conventional myosins. By contrast, the remaining approx. 51 kDa of sequence shows no similarity to any portion of conventional myosin sequences, contains regions that are rich in glycine, proline, and alanine residues, and lacks the distinctive sequence characteristics of an ..cap alpha..-helical, coiled-coil structure. They conclude, therefore, that the protein is composed of a myosin globular head fused not to the typical coiled-coil rod-like myosin tail structure but rather to an unusual carboxyl-terminal domain. These results support the conclusion that filamentous myosin is not required for force generation and provide a further perspective on the structural requirements for myosin function. Finally, they find a striking conservation of intron/exon structure between this gene and a vertebrate muscle myosin gene. They discuss this observation in relation to the evolutionary origin of the myosin IB gene and the antiquity of myosin gene intron/exon structure.
- Research Organization:
- National Institutes of Health, Bethesda, MD (USA)
- OSTI ID:
- 7242251
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 84:19; ISSN PNASA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
AMOEBA
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EVOLUTION
BODY
DAYS LIVING RADIOISOTOPES
DNA SEQUENCING
GENES
GLOBULINS
IN VITRO
INVERTEBRATES
ISOTOPES
LIGHT NUCLEI
MAMMALS
MAN
MICROORGANISMS
MOLECULAR STRUCTURE
MYOSIN
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PRIMATES
PROTEINS
PROTOZOA
RADIOISOTOPES
RATS
RODENTS
SARCODINA
SKELETON
STRUCTURAL CHEMICAL ANALYSIS
VERTEBRATES