Drebrin is a widespread actin-associating protein enriched at junctional plaques, defining a specific microfilament anchorage system in polar epithelial cells
Wk. Peitsch et al., Drebrin is a widespread actin-associating protein enriched at junctional plaques, defining a specific microfilament anchorage system in polar epithelial cells, EUR J CELL, 78(11), 1999, pp. 767-778
Using immunoblotting, immunprecipitation with subsequent fragment mass spec
trometry, and immunolocalization techniques, we have detected the actin-bin
ding ca. 120-kDa protein drebrin, originally identified in - and thought to
be specific for - neuronal cells, in diverse kinds of human and bovine non
neuronal cells. Drebrin has been found in numerous cell culture lines and i
n many tissues of epithelial, endothelial, smooth muscle and neural origin
but not in, for example, cardiac, skeletal and certain types of smooth musc
le cells, in hepatocytes and in the human epithelium-derived cell culture l
ine A-431, By double-label fluorescence microscopy we have found drebrin en
riched in actin microfilament bundles associated,vith plaques of cell-cell
contact sites representing adhering junctions. These drebrin-positive, adhe
ring junction-associated bundles, however, are not identical with the vincu
lin-containing, junction-attached bundles, and in the same cell both subtyp
es of microfilament-anchoring plaques are readily distinguished by immunolo
calization comparing drebrin and vinculin, The intracellular distribution o
f the drebrin- and the vinculin-based microfilament systems has been studie
d in detail by confocal fluorescence laser scanning microscopy in monolayer
s of the polar epithelial cell lines, MCF-7 and PLC, and drebrin has been f
ound to be totally and selectively absent in the notoriously vinculin-rich
focal adhesions. The occurrence and the possible functions of drebrin in no
n-neuronal cells, notably epithelial cells, and the significance of the exi
stence of two different actin-anchoring junctional plaques is discussed.