CLU: Isoform 1 functions as extracellular chaperone that prevents aggregation of nonnative proteins. Prevents stress- induced aggregation of blood plasma proteins. Inhibits formation of amyloid fibrils by APP, APOC2, B2M, CALCA, CSN3, SNCA and aggregation-prone LYZ variants (in vitro). Does not require ATP. Maintains partially unfolded proteins in a state appropriate for subsequent refolding by other chaperones, such as HSPA8/HSC70. Does not refold proteins by itself. Binding to cell surface receptors triggers internalization of the chaperone-client complex and subsequent lysosomal or proteasomal degradation. Secreted isoform 1 protects cells against apoptosis and against cytolysis by complement. Intracellular isoforms interact with ubiquitin and SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complexes and promote the ubiquitination and subsequent proteasomal degradation of target proteins. Promotes proteasomal degradation of COMMD1 and IKBKB. Modulates NF-kappa-B transcriptional activity. Nuclear isoforms promote apoptosis. Mitochondrial isoforms suppress BAX-dependent release of cytochrome c into the cytoplasm and inhibit apoptosis. Plays a role in the regulation of cell proliferation. Belongs to the clusterin family. 5 isoforms of the human protein are produced by alternative splicing.
Protein type: Secreted, signal peptide; Apoptosis; Secreted; Mitochondrial
Cellular Component: extracellular matrix; extracellular space; neuron projection; growth cone; intracellular membrane-bound organelle; membrane; mitochondrion; endoplasmic reticulum; perinuclear region of cytoplasm; cytoplasm; extracellular region; cytoplasmic vesicle; nucleus
Molecular Function: protein binding; ubiquitin protein ligase binding; protein N-terminus binding; misfolded protein binding
Biological Process: cell death; response to misfolded protein; positive regulation of nitric oxide biosynthetic process; protein stabilization; positive regulation of apoptosis; cell morphogenesis; microglial cell activation; positive regulation of tumor necrosis factor production; endocrine pancreas development; activation of NF-kappaB transcription factor; negative regulation of protein homooligomerization; myelin maintenance in the central nervous system; positive regulation of proteasomal ubiquitin-dependent protein catabolic process; protein import; positive regulation of cell proliferation; chaperone-mediated protein complex assembly; positive regulation of cell differentiation; neurite morphogenesis; negative regulation of apoptosis
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