The neuronal adaptor protein X11alpha interacts with the copper chaperone for SOD1 and regulates SOD1 activity.
The neuronal adaptor protein X11alpha participates in the formation of multiprotein complexes and intracellular trafficking. It contains a series of discrete protein-protein interaction domains including two contiguous C-terminal PDZ domains. We used the yeast two-hybrid system to screen for proteins that interact with the PDZ domains of human X11alpha, and we isolated a clone encoding domains II and III of the copper chaperone for Cu,Zn-superoxide dismutase-1 (CCS). The X11alpha/CCS interaction was confirmed in coimmunoprecipitation studies plus glutathione S-transferase fusion protein pull-down assays and was shown to be mediated via PDZ2 of X11alpha and a sequence within the carboxyl terminus of domain III of CCS. CCS delivers the copper cofactor to the antioxidant superoxide dismutase-1 (SOD1) enzyme and is required for its activity. Overexpression of X11alpha inhibited SOD1 activity in transfected Chinese hamster ovary cells which suggests that X11alpha binding to CCS is inhibitory to SOD1 activation. X11alpha also interacts with another copper-binding protein found in neurons, the Alzheimer's disease amyloid precursor protein. Thus, X11alpha may participate in copper homeostasis within neurons.
McLoughlin
D M
DM
Department of Neuroscience, Section of Old Age Psychiatry, Institute of Psychiatry, Denmark Hill, London SE5 8AF, United Kingdom.
Standen
C L
CL
Lau
K F
KF
Ackerley
S
S
Bartnikas
T P
TP
Gitlin
J D
JD
Miller
C C
CC
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D006801:Humans; D008565:Membrane Proteins; D018832:Molecular Chaperones / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014162:Transfection; D020798:Two-Hybrid System Techniques
C079091:APBA1 protein, human; D048868:Adaptor Proteins, Signal Transducing; C513071:Apba1 protein, rat; C114678:CCS protein, human; D002352:Carrier Proteins; C491961:Ccs protein, rat; D008565:Membrane Proteins; D018832:Molecular Chaperones; D009419:Nerve Tissue Proteins; D013482:Superoxide Dismutase