ISSN:
1432-0878
Keywords:
Amoeba proteus
;
Extraction of myosin
;
Synthetic and native myosin filaments
;
Structural analysis (negative staining)
;
Filament growth and aggregation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Synthetic and native myosin filaments were obtained from Amoeba proteus and their structure and aggregation mode were investigated by the negative staining technique. The existence of myosin in Amoeba proteus was further confirmed by biochemical and morphological data. Synthetic filaments up to 1.5 μm in length were formed from a crude myosin extract by dialysis against low ionic strength. These filaments clearly exhibit two structural features: 1. A periodical transverse banding with a repeat of about 140 Å resulting from the regular arrangement of the heads as well as of the rod portions of the myosin molecules. 2. A structural asymmetry due to the position and shape of two bare regions which are not covered with myosin heads. During filament elongation the bare regions remain in a constant position near the tips of the filaments. Thus, only in small filaments the bare regions fuse to form a central bare zone, whereas in filaments longer than 0.8 μm a central bare zone is lacking. Native filaments from amoeba homogenates revealed the same structural details as the synthetic filaments, suggesting that the same construction principle of the filaments is also realized in vivo. The mode of aggregation of Amoeba proteus myosin differs from that of cross-striated muscle myosin. These results are discussed in relation to the recently reported filament structure of vertebrate smooth muscle and slime mould myosin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00224543
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