Demonstration of a β‐type adaptin at the plant plasma membrane

Highly purified plasma membrane was prepared from etiolated zucchini hypocotyls, developing pea cotyledons and suspension‐cultured soybean cells by phase partitioning and sucrose density gradient centrifugation. The brain β‐adaptin monoclonal antibody B1/M6, which recognizes a similar adaptin in zucchini clathrin coated vesicles, cross‐reacted with an electrophoretically identical polypeptide in the plant plasma membrane fractions. Immunogold labelling of thin sections of soybean cells confirmed the presence of the β‐adaptin at the plasma membrane. The presence of this adaptin at the Golgi apparatus could not be demonstrated unequivocally.