Human rabaptin-5 is selectively cleaved by caspase-3 during apoptosis.
We have previously shown that Xenopus rabaptin-5 is cleaved in apoptotic extracts, with a concomitant reduction in the ability of these extracts to support endosomal membrane fusion (Cosulich, S. C., Horiuchi, H., Zerial, M., Clarke, P. R., and Woodman, P. G. (1997) EMBO J. 16, 6182-6191). In this report we demonstrate that caspase-dependent cleavage is a conserved feature of rabaptin-5. Human rabaptin-5 is cleaved at two sites (HSLD(379) and DESD(438)) in apoptotic HeLa extracts. Cleavage is effected by caspase-3, since it is prevented when caspase-3 activity is either inhibited by Ac-DEVD-CHO or removed by immunodepletion. Moreover, an identical pattern of cleavage is observed using recombinant caspase-3. The action of caspase-3 is highly selective; neither caspase-2 nor caspase-7 are able to cleave recombinant or cytosolic rabaptin-5. Caspase-dependent cleavage of rabaptin-5 generates two physically separated coiled coil-forming domains, the C-terminal of which retains the ability to bind the Rab5 exchange factor rabex-5.
Swanton
E
E
School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
Bishop
N
N
Woodman
P
P
D001483:Base Sequence; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D017931:DNA Primers; D006801:Humans; D006868:Hydrolysis; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D033921:Vesicular Transport Proteins
D017931:DNA Primers; D008565:Membrane Proteins; C097227:RABEP1 protein, human; D011994:Recombinant Proteins; D033921:Vesicular Transport Proteins; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases