Keith R. Willison

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The anaphase-promoting complex (APC) is a multisubunit E3 ubiquitin ligase that targets specific cell cycle-related proteins for degradation, regulating progression from metaphase to anaphase and exit from mitosis. The APC is regulated by binding of the coactivator proteins Cdc20p and Cdh1p, and by phosphorylation. We have developed a purification strategy(More)
Chaperonins assist the folding of other proteins. Type II chaperonins, such as chaperonin containing TCP-1(CCT), are found in archaea and in the eukaryotic cytosol. They are hexadecameric or nonadecameric oligomers composed of one to eight different polypeptides. Whereas type I chaperonins like GroEL are promiscuous, assisting in the folding of many other(More)
The murine t-complex encodes t-complex polypeptide-1 (TCP1), which is constitutively expressed in almost all cells, and upregulated during spermatogenesis. Mammalian sequences have greater than 96% identity with each other, and greater than 60% identity with Drosophila melanogaster and yeast orthologues. TCP1 is essential in yeast, and is postulated to be(More)
A collection of chaperonin containing TCP1 (CCT) micro-complexes that are comprised of subsets of the constitutively expressed CCT subunits have been identified. These CCT micro-complexes have mol. wts ranging from 120 to 250 kDa and are present in cells at lower abundance (<5%) as compared with intact CCT. Biochemical characterization of these(More)
The type II chaperonin CCT (chaperonin containing Tcp-1) of eukaryotic cytosol is a heteromeric 16-mer particle composed of eight different subunits. Three-dimensional reconstructions of apo-CCT and ATP-CCT have been obtained at 28 Å resolution by cryo-electron microscopy. Binding of ATP generates an asymmetric particle; one ring has a slightly different(More)
Many proteins in the cell require assistance from molecular chaperones at stages in their life cycles in order to attain correctly folded states and functional conformations during protein synthesis or during recovery from denatured states. A recently discovered molecular chaperone, which is abundant in the eukaryotic cytosol and is called the chaperonin(More)
Three-dimensional reconstruction from cryoelectron micrographs of the eukaryotic cytosolic chaperonin CCT complexed to tubulin shows that CCT interacts with tubulin (both the alpha and beta isoforms) using five specific CCT subunits. The CCT-tubulin interaction has a different geometry to the CCT-actin interaction, and a mixture of shared and unique CCT(More)
BACKGROUND TCP-1 is a 60 kD subunit of a cytosolic hetero-oligomeric chaperone that is known to be involved in the folding of actin and tubulin. This protein is a member of the chaperonin family, which includes Escherichia coli GroEL, the mitochondrial heat-shock protein Hsp60, the plastid Rubisco-subunit-binding protein and the archaebacterial protein(More)
The eukaryotic cytosolic chaperonin containing TCP-1 (CCT) has an important function in maintaining cellular homoeostasis by assisting the folding of many proteins, including the cytoskeletal components actin and tubulin. Yet the nature of the proteins and cellular pathways dependent on CCT function has not been established globally. Here, we use proteomic(More)
Folding to completion of actin and tubulin in the eukaryotic cytosol requires their interaction with cytosolic chaperonin CCT [chaperonin containing tailless complex polypeptide 1 (TCP-1)]. Three-dimensional reconstructions of nucleotide-free CCT complexed to either actin or tubulin show that CCT stabilizes both cytoskeletal proteins in open and(More)