March 7, 2005
by Karin Jegalian

Connections between cells are critical for everything from embryonic development to holding the nervous system together. One of the ways that cells keep in contact is through fingerlike projections called neural cell adhesion molecules (NCAMs) that attach to the same molecules on neighboring cells. Exactly how these molecules bind to each other has been the subject of intense study, resulting in two, seemingly contradictory models. One model postulates that the NCAMs overlap just at their ends, as if the cells are touching each other by their fingertips. The other model supposes that the NCAMs overlap much more extensively, as if the cells are holding each others' hands palm to palm.

New research by Deborah Leckband, Ph.D., of the University of Illinois at Urbana-Champaign shows that both models are correct. Leckband measured the strength of the attachments between cell membranes at various microscopic distances and found that strong attachments occur at two clearly defined lengths, each corresponding to one of the competing models.

In addition to reconciling earlier research findings, Leckband's results offer fresh hints about how NCAMs work. The different bonding arrangements may reflect a two-step process by which cells adhere—as if first touching their fingertips before forming a tighter clasp. Alternatively, having two bonding configurations could allow cells to adjust their proximity to serve different needs. Studying how cells connect to each other not only sheds light on a critical life process, it will also help scientists better understand—and someday perhaps prevent—birth defects and certain cancers.