Pix1 and Pix2 are novel WD40 microtubule-associated proteins that colocalize with mitochondria in Xenopus germ plasm and centrosomes in human cells.
In many animals, the germ line develops from a distinct mitochondria-rich region of embryonic cytoplasm called the germ plasm. However, the protein composition of germ plasm and its formation remain poorly understood, except in Drosophila. Here, we show that Xpat, a recently identified protein component of Xenopus germ plasm, interacts via its C-terminal domain with a novel protein, xPix1. Xpat and xPix1 are co-expressed in ovaries, eggs and early embryos and colocalize to the mitochondrial cloud and germ plasm in stage I and stage VI oocytes, respectively. Although Xpat appears unique to Xenopus, Pix proteins, which contain an N-terminal WD40 domain and C-terminal coiled-coil, are widely conserved. In humans, two proteins, Pix1 and Pix2, are expressed at varying levels in different cancer cell lines. Importantly, as well as localizing to mitochondria, human Pix proteins localize to centrosomes and associate with microtubules in vitro and in vivo. Although, Pix proteins are stably expressed through the cell cycle, Pix2 concentrates on microtubule structures in mitosis and microinjection of Pix antibodies interferes with cell division. Based on these data, we propose that Pix1 and Pix2 are microtubule-associated adaptor proteins that likely contribute to a range of developmental and cell division processes.
Hames
Rebecca S
RS
Department of Biochemistry, University of Leicester, University Road, Leicester LE1 9HN, UK.
Hames
Richard
R
Prosser
Suzanna L
SL
Euteneuer
Ursula
U
Lopes
Carla A M
CA
Moore
Wendy
W
Woodland
Hugh R
HR
Fry
Andrew M
AM
D000818:Animals; D019556:COS Cells; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D018385:Centrosome / Q000378:metabolism* / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D051179:Plakins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D029867:Xenopus Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism*
D008869:Microtubule-Associated Proteins; C113822:PGAT protein, Xenopus; D051179:Plakins; D014157:Transcription Factors; D029867:Xenopus Proteins