Porcine myosin-VI: characterization of a new mammalian unconventional myosin.
We have cloned a new mammalian unconventional myosin, porcine myosin-VI from the proximal tubule cell line, LLC-PK1 (CL4). Porcine myosin-VI is highly homologous to Drosophila 95F myosin heavy chain, and together these two myosins comprise a sixth class of myosin motors. Myosin-VI exhibits ATP-sensitive actin-binding activities characteristic of myosins, and it is associated with a calmodulin light chain. Within LLC-PK1 cells, myosin-VI is soluble and does not associate with the major actin-containing domains. Within the kidney, however, myosin-VI is associated with sedimentable structures and specifically locates to the actin- and membrane-rich apical brush border domain of the proximal tubule cells. This motor was not enriched within the glomerulus, capillaries, or distal tubules. Myosin-VI associates with the proximal tubule cytoskeleton in an ATP-sensitive fashion, suggesting that this motor is associated with the actin cytoskeleton within the proximal tubule cells. Given the difference in association of myosin-VI with the apical cytoskeleton between LLC-PK1 cells and adult kidney, it is likely that this cell line does not fully differentiate to form functional proximal tubule cells. Myosin-VI may require the presence of additional elements, only found in vivo in proximal tubule cells, to properly locate to the apical domain.
Hasson
T
T
Department of Biology, Yale University, New Haven, Connecticut 06520.
Mooseker
M S
MS
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002147:Calmodulin / Q000737:chemistry; D002460:Cell Line; D003001:Cloning, Molecular; D004330:Drosophila / Q000737:chemistry / Q000235:genetics; D015151:Immunoblotting; D007687:Kidney Tubules, Proximal / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018995:Myosin Heavy Chains; D009218:Myosins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013552:Swine
D000199:Actins; D002147:Calmodulin; C089785:myosin VI; D000255:Adenosine Triphosphate; D018995:Myosin Heavy Chains; D009218:Myosins