PROBLEM TO BE SOLVED: To provide a method, etc., for obtaining a substance useful for therapeutic agents and preventives for diseases accompanying platelet aggregation by finding out a new gene associated with the platelet aggregation. SOLUTION: The invention relates to a method of screening a compound relating to platelet aggregation by using gp44 which is a factor relating to platelet aggregation, an activity measurement method, a compound obtained by the above method, a kit to be used in the method and a mutant polypeptide losing a platelet aggregation activity, and relates to a model animal, a diagnosis method, and a medicinal composition for treating or preventing such diseases associated with platelet aggregation. COPYRIGHT: (C)2005,JPO&NCIPI
