Biomaterial Database

C termini of proteasomal ATPases play nonequivalent roles in cellular assembly of mammalian 26 S proteasome. 2011

Young-Chan Kim, and George N DeMartino

Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9040, USA.

The 26 S proteasome comprises two multisubunit subcomplexes as follows: 20 S proteasome and PA700/19 S regulatory particle. The cellular mechanisms by which these subcomplexes assemble into 26 S proteasome and the molecular determinants that govern the assembly process are poorly defined. Here, we demonstrate the nonequivalent roles of the C termini of six AAA subunits (Rpt1-Rpt6) of PA700 in 26 S proteasome assembly in mammalian cells. The C-terminal HbYX motif (where Hb is a hydrophobic residue, Y is tyrosine, and X is any amino acid) of each of two subunits, Rpt3 and Rpt5, but not that of a third subunit Rpt2, was essential for assembly of 26 S proteasome. The C termini of none of the three non-HbYX motif Rpt subunits were essential for cellular 26 S proteasome assembly, although deletion of the last three residues of Rpt6 destabilized the 20 S-PA700 interaction. Rpt subunits defective for assembly into 26 S proteasome due to C-terminal truncations were incorporated into intact PA700. Moreover, intact PA700 accumulated as an isolated subcomplex when cellular 20 S proteasome content was reduced by RNAi. These results indicate that 20 S proteasome is not an obligatory template for assembly of PA700. Collectively, these results identify specific structural elements of two Rpt subunits required for 26 S proteasome assembly, demonstrate that PA700 can be assembled independently of the 20 S proteasome, and suggest that intact PA700 is a direct intermediate in the cellular pathway of 26 S proteasome assembly.

UI	MeSH Term	Description	Entries
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000251	Adenosine Triphosphatases	A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.	ATPases,Adenosinetriphosphatase,ATPase,ATPase, DNA-Dependent,Adenosine Triphosphatase,DNA-Dependent ATPase,DNA-Dependent Adenosinetriphosphatases,ATPase, DNA Dependent,Adenosinetriphosphatases, DNA-Dependent,DNA Dependent ATPase,DNA Dependent Adenosinetriphosphatases,Triphosphatase, Adenosine
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D017384	Sequence Deletion	Deletion of sequences of nucleic acids from the genetic material of an individual.	Deletion Mutation,Deletion Mutations,Deletion, Sequence,Deletions, Sequence,Mutation, Deletion,Mutations, Deletion,Sequence Deletions
D017434	Protein Structure, Tertiary	The level of protein structure in which combinations of secondary protein structures (ALPHA HELICES; BETA SHEETS; loop regions, and AMINO ACID MOTIFS) pack together to form folded shapes. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure.	Tertiary Protein Structure,Protein Structures, Tertiary,Tertiary Protein Structures
D046988	Proteasome Endopeptidase Complex	A large multisubunit complex that plays an important role in the degradation of most of the cytosolic and nuclear proteins in eukaryotic cells. It contains a 700-kDa catalytic sub-complex and two 700-kDa regulatory sub-complexes. The complex digests ubiquitinated proteins and protein activated via ornithine decarboxylase antizyme.	20S Proteasome,Ingensin,Macropain,Macroxyproteinase,Multicatalytic Endopeptidase Complex,Multicatalytic Proteinase,Prosome,Proteasome,Complex, Multicatalytic Endopeptidase,Complex, Proteasome Endopeptidase,Endopeptidase Complex, Multicatalytic,Endopeptidase Complex, Proteasome,Proteasome, 20S,Proteinase, Multicatalytic
D057809	HEK293 Cells	A cell line generated from human embryonic kidney cells that were transformed with human adenovirus type 5.	293T Cells,HEK 293 Cell Line,HEK 293 Cells,Human Embryonic Kidney Cell Line 293,Human Kidney Cell Line 293,293 Cell, HEK,293 Cells, HEK,293T Cell,Cell, 293T,Cell, HEK 293,Cell, HEK293,Cells, 293T,Cells, HEK 293,Cells, HEK293,HEK 293 Cell,HEK293 Cell
D020816	Amino Acid Motifs	Three-dimensional protein structural elements that are composed of a combination of secondary structures. They include HELIX-LOOP-HELIX MOTIFS and ZINC FINGERS. Motifs are typically the most conserved regions of PROTEIN DOMAINS and are critical for domain function. However, the same motif may occur in proteins or enzymes with different functions.	AA Motifs,Motifs, Amino Acid,Protein Motifs,Protein Structure, Supersecondary,Supersecondary Protein Structure,AA Motif,Amino Acid Motif,Motif, AA,Motif, Amino Acid,Motif, Protein,Motifs, AA,Motifs, Protein,Protein Motif,Protein Structures, Supersecondary,Supersecondary Protein Structures