CHICK LAMININ - ISOLATION BY MONOCLONAL-ANTIBODIES AND DIFFERENTIAL DISTRIBUTION OF VARIANTS IN THE EMBRYO

In order to study the expression and function of laminin variants during chick embryonic development, we have generated monoclonal antibodies against chick heart laminin. One monoclonal antibody (mAb), called 9/F-10, could be used to purify chick laminin to homogeneity. By rotary shadowing, cross-shaped and T-shaped laminin particles as well as aggregates of two laminin molecules crosslinked via their short arms could be observed in this preparation. Purified chick laminin was very potent in mediating neurite growth by chick embryonic neurons. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of reduced chick heart laminin revealed a complex pattern of polypeptides which are immunologically related to several mammalian laminin chains. The two mAbs, 9/F-10 and 3/E-8, recognize two different types of chick laminin subunits. By immunofluorescence, antibody 3/E-8 labels basement membranes, aortic smooth muscle, and mesenchyme of 6-day-old chick embryos. In contrast, staining by mAb 9/F-10 is confined to basement membranes. Therefore, the two antibodies seem to distinguish between two different chick laminin isoforms. © 1991.