Interactions between the evolutionarily conserved, actin-related protein, Arp11, actin, and Arp1.
The dynein activator dynactin is a multiprotein complex with distinct microtubule- and cargo-binding domains. The cargo-binding domain contains a short, actin-like filament of the actin-related protein Arp1, a second actin-related protein, Arp11, and conventional actin. The length of this filament is invariant in dynactin isolated from multiple species and tissues, suggesting that activities that regulate Arp1 polymerization are important for dynactin assembly. Arp11 is present in a protein complex localized at the pointed end of the Arp1 minifilament, whereas actin capping protein (CapZ) is present at the barbed end. Either might cooperate with conventional actin to cap Arp1. We tested the ability of Arp11 to interact with conventional actin and found it could coassemble. Like Arp1, cytosolic Arp11 is found only in dynactin, suggesting that Arp11 and free cytosolic actin do not interact significantly. Recombinant Arp11 and Arp1 were demonstrated to interact by coprecipitation. We developed an in vivo assay for Arp11-Arp1 interaction based on previous observations that Arp1 forms filamentous assemblies when overexpressed in cultured cells. Arp11 significantly decreases the formation of these organized Arp1 assemblies. Finally, this assay was used to confirm the identity of a putative Arp11 homolog in Drosophila melanogaster.
Eckley
D Mark
DM
Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
Schroer
Trina A
TA
D051378:Actin-Related Protein 3; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D051347:CapZ Actin Capping Protein; D004268:DNA-Binding Proteins / Q000378:metabolism*; D000072159:Dynactin Complex; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000378:metabolism; D011485:Protein Binding; D011987:Receptors, Steroid; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013347:Subcellular Fractions; D014157:Transcription Factors / Q000378:metabolism*
D051378:Actin-Related Protein 3; D000199:Actins; D051837:COUP Transcription Factor II; D051836:COUP Transcription Factors; D051347:CapZ Actin Capping Protein; D004268:DNA-Binding Proteins; D000072159:Dynactin Complex; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D009124:Muscle Proteins; D011987:Receptors, Steroid; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C422070:ACTR3B protein, human; C095569:NR2F2 protein, human