Tai, Y: Studies On the Coxsackie and AdenovirusReceptor

CAR has recently been identified as a high affinity receptor for both Coxsackievirus and certain adenovirus (AV) serotypes. Virus bound by CAR is passed to integrins which bind an RGD (Arg-Gly-Asp) sequence in the viral penton base protein and act as secondary receptors responsible for virus internalization. Recent studies have shown that, in integrin- expressing cells, CAR can directly mediate AV uptake without penton base RGD-av integrin interactions. I confirmed that EC+ transmembrane (TM) domains of CAR are sufficient for AV uptake in integrin-expressing cells. CAR is the primary AV receptor and integrins are secondary AV receptors. To investigated the possibility that these proteins associate in a functional complex in the cell membrane, I forced CAR expression in a line of human myoblasts and obtained coprecipitation of CAR and B3 integrin suggesting these proteins may associate. I also found that mouse brain extract reproducibly modifies the immunoreactivity of the CAR C-terminal fusion protein and increase its tendency to dimerize. Mouse brain extracts also modified the isoelectric pH of the CAR C-terminal fusion protein.