HMW-2, the Sertoli cell cytoplasmic dynein from rat testis, is a dimer composed of nearly identical subunits.
The ultrastructure and biochemical characteristics of HMW-2, the Sertoli cell cytoplasmic dynein isolated from rat testes, were analyzed. Electron microscopic studies revealed a two-headed two-stem structure with dimensions very similar to other dyneins. We found that, like other cytoplasmic dyneins, both heads have an approximately spherical shape with a central cavity. Heavy chain analysis suggested the presence of only one type of heavy chain, a finding that was supported by the simple Michaelis-Menten kinetics displayed by the HMW-2-associated ATPase activity. In addition, dissociation of the HMW-2 complex resulted in a single type of dynein subunit sedimenting at 11.8 S. This fraction contained all the polypeptides present in the undissociated HMW-2. Ultrastructurally the HMW-2 subunits were composed of one globular domain with a tail. The simplest interpretation is that HMW-2 is a dimer of nearly identical subunits, each containing one heavy chain, one 90-kDa intermediate chain, and two light chains.
Neely
M D
MD
Department of Pathology, Brown University, Providence, Rhode Island 02912.
Erickson
H P
HP
Boekelheide
K
K
D000251:Adenosine Triphosphatases / Q000302:isolation & purification*; D000818:Animals; D003593:Cytoplasm / Q000201:enzymology; D004398:Dyneins / Q000302:isolation & purification* / Q000648:ultrastructure; D046911:Macromolecular Substances; D008297:Male; D008854:Microscopy, Electron; D008970:Molecular Weight; D051381:Rats; D012708:Sertoli Cells / Q000201:enzymology*
D046911:Macromolecular Substances; D000251:Adenosine Triphosphatases; D004398:Dyneins