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PDBsum entry 4g4s
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Hydrolase/chaperone
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PDB id
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4g4s
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Contents |
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241 a.a.
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246 a.a.
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237 a.a.
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220 a.a.
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250 a.a.
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235 a.a.
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246 a.a.
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196 a.a.
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220 a.a.
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203 a.a.
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195 a.a.
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212 a.a.
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222 a.a.
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233 a.a.
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200 a.a.
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190 a.a.
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References listed in PDB file
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Key reference
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Title
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Structure of a proteasome pba1-Pba2 complex: implications for proteasome assembly, Activation, And biological function.
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Authors
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B.M.Stadtmueller,
E.Kish-Trier,
K.Ferrell,
C.N.Petersen,
H.Robinson,
D.G.Myszka,
D.M.Eckert,
T.Formosa,
C.P.Hill.
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Ref.
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J Biol Chem, 2012,
287,
37371-37382.
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PubMed id
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Abstract
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The 20S proteasome is an essential, 28-subunit protease that sequesters
proteolytic sites within a central chamber, thereby repressing substrate
degradation until proteasome activators open the entrance/exit gate. Two
established activators, Blm10 and PAN/19S, induce gate opening by binding to the
pockets between proteasome α-subunits using C-terminal HbYX
(hydrophobic-tyrosine-any residue) motifs. Equivalent HbYX motifs have been
identified in Pba1 and Pba2, which function in proteasome assembly. Here, we
demonstrate that Pba1-Pba2 proteins form a stable heterodimer that utilizes its
HbYX motifs to bind mature 20S proteasomes in vitro and that the Pba1-Pba2 HbYX
motifs are important for a physiological function of proteasomes, the
maintenance of mitochondrial function. Other factors that contribute to
proteasome assembly or function also act in the maintenance of mitochondrial
function and display complex genetic interactions with one another, possibly
revealing an unexpected pathway of mitochondrial regulation involving the
Pba1-Pba2 proteasome interaction. Our determination of a proteasome Pba1-Pba2
crystal structure reveals a Pba1 HbYX interaction that is superimposable with
those of known activators, a Pba2 HbYX interaction that is different from those
reported previously, and a gate structure that is disrupted but not sufficiently
open to allow entry of even small peptides. These findings extend understanding
of proteasome interactions with HbYX motifs and suggest multiple roles for
Pba1-Pba2 interactions throughout proteasome assembly and function.
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