A Dynactin Subunit with a Highly Conserved Cysteine-rich Motif Interacts Directly with Arp1

Dynactin is a multisubunit complex and a required cofactor for most, or all, of the cellular processes powered by the microtubule-based motor cytoplasmic dynein. Using a dynein affinity column, the previously uncharacterized p62 subunit of dynactin was isolated and microsequenced. Two peptide sequen...

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Bibliographic Details
Published in:The Journal of biological chemistry 2000-02, Vol.275 (7), p.4834-4839
Main Authors: Karki, Sher, Tokito, Mariko K., Holzbaur, Erika L.F.
Format: Article
Language:English
Subjects:
Amino Acid Motifs
Amino Acid Sequence
Animals
Arp1 protein
Cell Line
Cloning, Molecular
Conserved Sequence
COUP Transcription Factor II
COUP Transcription Factors
Cysteine - analysis
DNA, Complementary
DNA-Binding Proteins - metabolism
dynactin
Dynactin Complex
Humans
Microtubule-Associated Proteins - chemistry
Microtubule-Associated Proteins - genetics
Microtubule-Associated Proteins - metabolism
p62 protein
Protein Binding
Receptors, Steroid
Sequence Homology, Amino Acid
Transcription Factors - metabolism
Transfection
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Summary:Dynactin is a multisubunit complex and a required cofactor for most, or all, of the cellular processes powered by the microtubule-based motor cytoplasmic dynein. Using a dynein affinity column, the previously uncharacterized p62 subunit of dynactin was isolated and microsequenced. Two peptide sequences were used to clone human cDNAs encoding p62. Sequence analysis of the predicted human polypeptide of 53 kDa revealed a highly conserved pattern of eleven cysteine residues, eight of which fit the consensus sequence for a Zn2+-binding RING domain. We have characterized p62 as an integral component of 20 S dynactin by biochemical and immunocytochemical methods. Affinity chromatography experiments demonstrate that p62 binds directly to the Arp1 subunit of dynactin. Immunocytochemistry with antibodies to p62 demonstrates that this polypeptide has a punctate cytoplasmic distribution as well as centrosomal distribution typical of dynactin. In transfected cells, overexpression of p62 did not disrupt microtubule organization or the integrity of the Golgi but did cause both cytosolic and nuclear distribution of the protein, suggesting that this polypeptide may be targeted to the nucleus at very high expression levels.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.275.7.4834