Queuosine metabolism: possible relation to B-cell activation by C8 derivatives of guanosine

The observed enhancement of B-lymphocyte activation by 8-bromoguanosine and 8-mercaptoguanosine is hypothesized to occur via a "binding protein" which requires a guanine nucleoside as the syn conformer for productive interaction. In addition, because of the 7-substituent, Q nucleoside also is hypothesized to bind as the syn conformer and, therefore, to be a potential B-lymphocyte activator.