TY - JOUR
T1 - Calcium mobilization is required for nuclear vesicle fusion in vitro
T2 - Implications for membrane traffic and IP3 receptor function
AU - Sullivan, Kathleen M.C.
AU - Busa, William B.
AU - Wilson, Katherine L.
N1 - Funding Information:
K. L. W. thanks Norm Richard, Hugh Crenshaw, Lily Wong, and Annick Le Gall, who performed pilot studies with calcium ionophores, BAPTA, and fura-at the 1992 Physiology Summer Course at Woods Hole, Massachusetts. We are grateful to Carolyn Machamer, Chris Wiese, Annette Boman, Sunil Hingorani, Paul Melancon, and Rob Jensen for lively discussions and critical reading of the manuscript and to Rick Kahn for antibodies to ARF. We thank Mike Delannoy for help with the electron microscopy. This work was supported by a predoctoral fellowship from the National Science Foundation to K. M. C. S. and by a research grant and junior faculty research award, both to K. L. W., from the American Cancer Society.
PY - 1993/7/2
Y1 - 1993/7/2
N2 - We studied the fusion of nuclear vesicles bound to chromatin in Xenopus egg extracts. Fusion was inhibited by 5 mM BAPTA, a Ca2+ buffer that suppresses cytosolic [Ca2+] gradients. The BAPTA-inhibited step in fusion was biochemically distinct from, and occurred later than, the GTPγS-sensitive step mediated by the monomeric GTPase, ADP-ribosylation factor. Exogenous inositol 1,4,5-trisphosphate (IP3), which triggers Ca2+ release from lumenal stores via IP3 receptors, stimulated fusion in the presence of BAPTA. This rescue was specific, because inositol 1,3,4-trisphosphate had no effect. Heparin, a potent antagonist of IP3 receptors, independently blocked fusion in an IP3-reversible manner. We suggest that phosphoinositide signaling may regulate nuclear vesicle fusion.
AB - We studied the fusion of nuclear vesicles bound to chromatin in Xenopus egg extracts. Fusion was inhibited by 5 mM BAPTA, a Ca2+ buffer that suppresses cytosolic [Ca2+] gradients. The BAPTA-inhibited step in fusion was biochemically distinct from, and occurred later than, the GTPγS-sensitive step mediated by the monomeric GTPase, ADP-ribosylation factor. Exogenous inositol 1,4,5-trisphosphate (IP3), which triggers Ca2+ release from lumenal stores via IP3 receptors, stimulated fusion in the presence of BAPTA. This rescue was specific, because inositol 1,3,4-trisphosphate had no effect. Heparin, a potent antagonist of IP3 receptors, independently blocked fusion in an IP3-reversible manner. We suggest that phosphoinositide signaling may regulate nuclear vesicle fusion.
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U2 - 10.1016/0092-8674(93)90366-X
DO - 10.1016/0092-8674(93)90366-X
M3 - Article
C2 - 8391933
AN - SCOPUS:0027175035
SN - 0092-8674
VL - 73
SP - 1411
EP - 1422
JO - Cell
JF - Cell
IS - 7
ER -