The 193-kD vault protein, VPARP, is a novel poly(ADP-ribose) polymerase.
Mammalian vaults are ribonucleoprotein (RNP) complexes, composed of a small ribonucleic acid and three proteins of 100, 193, and 240 kD in size. The 100-kD major vault protein (MVP) accounts for >70% of the particle mass. We have identified the 193-kD vault protein by its interaction with the MVP in a yeast two-hybrid screen and confirmed its identity by peptide sequence analysis. Analysis of the protein sequence revealed a region of approximately 350 amino acids that shares 28% identity with the catalytic domain of poly(ADP-ribose) polymerase (PARP). PARP is a nuclear protein that catalyzes the formation of ADP-ribose polymers in response to DNA damage. The catalytic domain of p193 was expressed and purified from bacterial extracts. Like PARP, this domain is capable of catalyzing a poly(ADP-ribosyl)ation reaction; thus, the 193-kD protein is a new PARP. Purified vaults also contain the poly(ADP-ribosyl)ation activity, indicating that the assembled particle retains enzymatic activity. Furthermore, we show that one substrate for this vault-associated PARP activity is the MVP. Immunofluorescence and biochemical data reveal that p193 protein is not entirely associated with the vault particle, suggesting that it may interact with other protein(s). A portion of p193 is nuclear and localizes to the mitotic spindle.
Kickhoefer
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VA
Department of Biological Chemistry, University of California, Los Angeles School of Medicine, Los Angeles, California 90095-1737, USA. vkick@medne.tucla.edu
Siva
A C
AC
Kedersha
N L
NL
Inman
E M
EM
Ruland
C
C
Streuli
M
M
Rome
L H
LH
D000510:Alpha-Globulins / Q000737:chemistry / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D019313:BRCA1 Protein / Q000737:chemistry / Q000235:genetics; D019556:COS Cells; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D002467:Cell Nucleus / Q000201:enzymology; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000201:enzymology; D005347:Fibroblasts; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000201:enzymology; D020394:Vault Ribonucleoprotein Particles / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015003:Yeasts / Q000235:genetics; D000099187:Major Vault Protein
D000510:Alpha-Globulins; D019313:BRCA1 Protein; D010446:Peptide Fragments; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases; D012333:RNA, Messenger; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein; C011877:inter-alpha-inhibitor