Myosin II is involved in the production of constitutive transport vesicles from the TGN.
The participation of nonmuscle myosins in the transport of organelles and vesicular carriers along actin filaments has been documented. In contrast, there is no evidence for the involvement of myosins in the production of vesicles involved in membrane traffic. Here we show that the putative TGN coat protein p200 (Narula, N., I. McMorrow, G. Plopper, J. Doherty, K.S. Matlin, B. Burke, and J.L. Stow. 1992. J. Cell Biol. 114: 1113-1124) is myosin II. The recruitment of myosin II to Golgi membranes is dependent on actin and is regulated by G proteins. Using an assay that studies the release of transport vesicles from the TGN in vitro, we provide functional evidence that p200/myosin is involved in the assembly of basolateral transport vesicles carrying vesicular stomatitis virus G protein (VSVG) from the TGN of polarized MDCK cells. The 50% reduced efficiency in VSVG vesicle release from the TGN in vitro after depletion of p200/myosin II could be reestablished to control levels by the addition of purified nonmuscle myosin II. Several inhibitors of the actin-stimulated ATPase activity of myosin specifically inhibited the release of VSVG-containing vesicles from the TGN.
Müsch
A
A
Dyson Institute of Vision Research, Department of Ophthalmology, Department of Cell Biology and Anatomy, Cornell University Medical College, New York 10021, USA.
Cohen
D
D
Rodriguez-Boulan
E
E
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D001792:Blood Platelets / Q000737:chemistry; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D019204:GTP-Binding Proteins / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D006388:Hemagglutinins / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D008099:Liver; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009218:Myosins / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D014759:Viral Envelope Proteins / Q000378:metabolism
D000199:Actins; C028391:G protein, vesicular stomatitis virus; D006388:Hemagglutinins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D014759:Viral Envelope Proteins; D019204:GTP-Binding Proteins; D009218:Myosins