Chymotrypsin sensitivity of COAT-platelets.

Gel-filtered platelets were activated with both convulxin and thrombin in the presence of b-BSA-(5-HT)₆ and stained with phycoerythrin-streptavidin.7 (A) COAT-platelets6 bind b-BSA-(5-HT)₆ (filled histogram; region M1) while resting platelets do not (dashed histogram). (B) A brief exposure of platelets to chymotrypsin prior to activation has only a modest effect on b-BSA-(5-HT)₆binding. However, chymotrypsin treatment after activation essentially eliminates retention of b-BSA-(5-HT)₆ (C; region M1). (D) The concentration dependence for chymotrypsin (abscissa) inhibition of COAT-platelet production (ordinate).