Identification and organization of the components in the isolated microvillus cytoskeleton.
We have examined the effects of ATP and deoxycholate (DOC) on the cytoskeletal organization of Triton-demembranated microvilli (MV) isolated from chicken intestine brush borders. Isolated MV are composed of a core of tightly bundled microfilaments from which arms project laterally to the plasma membrane with a 33-nm periodicity. These lateral arms spiral around the core microfilaments as a helix with a 25 degrees pitch. Demembranated MV consist of four polypeptides with mol wt of 110,000, 95,000, 68,000, and 42,000, present in molar ratios of 1.1:1.6:1.3:10.0. After addition of 50 microM ATP and 0.1 mM Mg++, the cytoskeletons are organized as a tight bundle of microfilaments from which lateral arms are missing. In these ATP-treated cytoskeletons, the 110-kdalton polypeptide is reduced in amount and the 95,000, 68,000, and 42,000 polypeptides are present in a 1.3:1.2:10.0 ratio. In contrast, after incubation with 0.5% DOC, the core microfilaments are no longer tightly bundled yet the lateral arms remain attached with a distinct 33-nm periodicity. These DOC-treated cytoskeletons are depleted of the 95,000 and 68,000 polypeptides and are composed of the 110,000 and 42,000 polypeptides in a 2:10 molar ratio. These results suggest that the microfilaments are associated into a core bundle by the 95- and 68-kdalton polypeptides and from this core bundle project the lateral arms composed of the 110-kdalton polypeptide.
D000199:Actins / Q000032:analysis; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000032:analysis*; D002645:Chickens; D003599:Cytoskeleton / Q000032:analysis* / Q000648:ultrastructure; D003840:Deoxycholic Acid / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008871:Microvilli / Q000032:analysis* / Q000187:drug effects / Q000648:ultrastructure; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis*
D000199:Actins; D010455:Peptides; D003840:Deoxycholic Acid; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate