Mechanism of interferon action--the discovery of the pppA2'p5'A2'p5'A receptor.

In this paper it is demonstrated that (3H)2'-5'P3A3 can bind to the peritoneal macrophages from Wistar rat. This binding is strongly inhibited by cold 2'-5'P3A3, while the inhibiting capacity of 2'-5'P3I3 and 2'-5'A3 is very small, showing that this binding is highly specific. And the binding of (3H)2'-5'P3A3 is reversible, saturable and with high affinity. A Scatchard analysis of the binding data gives a linear plot, an apparent dissociation constant (Kd) about 1.3 X 10(-7) M and binding sites per cell about 2.1 X 10(7). The above evidence shows the existence of the 2'-5'P3A3 receptor, a fact which, to our knowledge, has not been reported before.