Fig. S9.

Isoleucine at position 13 in polyL25 is required for focus formation. (A) C127 cells were infected with low-titer retrovirus stocks of MSCV vector or MSCV expressing untagged polyL25 containing a single isoleucine at position 11, 12, 13, 14, or 15. Plates were stained with Giemsa 3 wk later. (B) Quantitation of focus forming assays performed as in A for untagged polyL25 traptamers, normalized for virus titer and expressed relative to E5 activity. Circles and triangles show independent experiments. Each symbol is the average of two plates of foci from a single infection.