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

Ca 2+ was found to influence the patterns of limit digests of laminin obtained with various neutral proteases. In the presence of Ca 2+ , 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 Ca 2+ . 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.