Limited proteolysis of the coxsackievirus and adenovirus receptor (CAR) onHeLa cells exposed to trypsin

Trypsin treatment of HeLa cells results in a limited proteolysis of the cox sackievirus and adenovirus receptor (CAR) after which the cleaved CAR remai ns cell-associated and tryptic peptides remain associated through disulfide bonds. Trypsin-treated HeLa cells remain susceptible to infection with cox sackievirus B and produce progeny virus at 8 h post-infection in amounts co mparable to cells with intact CAR. HeLa cells remove the proteolysed CAR wi thin 15 h and require over 24 h to restore intact CAR to control levels. As turnover is relatively slow, physiological functions that require intact C AR protein mag be compromised for more than 24 h following trypsin treatmen t. Moreover, since removal of proteolysed CAR proceeds at more than twice t he replacement rate, trypsin treatment disrupts the receptor-per-cell stead y state for at least 24 h, (C) 2000 Federation of European Biochemical Soci eties, Published by Elsevier Science B.V. All rights reserved.