Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents

This Article Full Text (PDF, 860K) PPT slides of all figures Correction (v177,p941) Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Powell, K. Search for Related Content PubMed Articles by Powell, K. Related Collections Related Article Social Bookmarking                            What's this?

Motoring microvillar membrane

Brush border apical membrane (red) accumulates at the tips of actin bundles (green) upon addition of ATP (right) and myosin-1a activation.

Just as intestines constantly shed gut cells, so too may gut cells shed their brush border membranes. On page 671, McConnell and Tyska show that microvillar myosin-1a pulls membrane for shedding along the core actin bundle.

Myosin-1a was first seen in micrographs 30 years ago bridging the actin bundle and the overlying membrane in microvilli. But it was not until 1989 that myosin-1a was characterized as an actin plus end–directed motor. Its potential as an active motor in the microvillus, rather than mere structural element, was overlooked until now.

A motor is useful in isolated brush borders, which dramatically shear off their membranes from the base to the tip of the microvillar stalks when fed ATP. McConnell and Tyska find that this actin plus end–directed shearing results in vesicles' being shed from the microvilli tips. The ATP activated shedding by turning on myosin-1a: brush borders from myosin-1a knock-out mice shed membrane at only five percent of the wild-type level.

How myosin-1a gains traction on the membrane surface is an open question. But the discovery promotes the brush border from merely a static scaffold of boosted surface area for nutrient breakdown to an active zone for shedding vesicles—tiny packets that may speed nutrient breakdown, shed invading microbes, send messages, and improve membrane remodeling.

Kendall Powell

kendall2{at}nasw.org

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

Related Article

Myosin-1a powers the sliding of apical membrane along microvillar actin bundles

Russell E. McConnell and Matthew J. Tyska
J. Cell Biol. 2007 177: 671-681. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF, 860K) PPT slides of all figures Correction (v177,p941) Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Powell, K. Search for Related Content PubMed Articles by Powell, K. Related Collections Related Article Social Bookmarking                            What's this?