K-INDUCED FUSION-FROM-WITHIN( IONOPHORES STIMULATE RETROVIRUS)

Fusion-from-without (FFWO) and fusion-from-within (FFWI) for Moloney M LV in SC-1 cells were selectively stimulated by the polycation polybre ne and the ionophore amphotericin B, which can be used to discriminate between the two fusion types. FFWI was stimulated by a number of diff erent K+ ionophores. The stimulation occurred within few hours, did no t require protein synthesis, and depended on the uninfected cell type, which suggests that FFWI is stimulated by a permutation of the K+ gra dient of the uninfected cell. Plasma membrane vesicles from infected c ells could also stimulate fusion with the same stimulation pattern as FFWI. (C) 1998 Elsevier Science B.V. All rights reserved.