Native alpha 2-macroglobulin binds to a surface component of human placental trophoblast

Immunofluorescence and radiobinding studies have shown that native human alpha 2-macroglobulin (alpha 2M), but not alpha 2M-trypsin complexes, binds to isolated human placental syncytiotrophoblast microvillous plasma membrane vesicles. Inhibition studies have indicated that alpha 2M may bind to a trophoblast surface protease. This interaction is of significance for the control of trophoblast invasiveness and haemostasis within the placental bed.