Binding of Ca2+ influences susceptibility of laminin to proteolytic digestion and interactions between domain-specific laminin fragments

Ca2+ was found to influence the patterns of limit digests of laminin obtained with various neutral proteases. In the presence of Ca2+, larger fragments were obtained from the central part of laminin than in its absence. This was interpreted as being due to a stabilization of the central short-arm domains of laminin by bound Ca2+. When proteolytic fragments were tested for their ability to aggregate, only large fragments containing intact short arms were active, indicating an important role for these domains in laminin self-aggregation.