Fig. 2.

CypA stimulates RNA binding by NS5A in a CsA-sensitive fashion. NS5A(ΔAH) (10 nM) was preincubated with increasing concentrations of GST-CypA (a) or GST (b) at 4°C in binding buffer. ³²P-labeled 3′ UTR RNA (1 nM) was added, and binding reactions proceeded for 30 min in binding buffer prior to washing and filter binding as described previously (6). The left hand bar shows the background RNA binding of either GST-CypA or GST in the absence of NS5A(ΔAH). (c) NS5A(ΔAH) (10 nM), ³²P-labeled 3′ UTR RNA (1 nM), and GST-CypA (100 nM) were incubated with increasing concentrations of CsA (0 to 1 μM). The left hand bar shows the background RNA binding of NS5A(ΔAH) in the presence of CsA (1 μM) and the absence of GST-CypA.