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Mol. Cell. Biol., Nov 1996, 6229-6241, Vol 16, No. 11
JP Borg, J Ooi, E Levy and B Margolis
The phosphotyrosine interaction (PI) domains (also known as the PTB, or
phosphotyrosine binding, domains) of Shc and IRS-1 are recently described
domains that bind peptides phosphorylated on tyrosine residues. The PI/PTB
domains differ from Src homology 2 (SH2) domains in that their binding
specificity is determined by residues that lie amino terminal and not
carboxy terminal to the phosphotyrosine. Recently, it has been appreciated
that other cytoplasmic proteins also contain PI domains. We now show that
the PI domain of X11 and one of the PI domains of FE65, two neuronal
proteins, bind to the cytoplasmic domain of the amyloid precursor protein
((beta)APP). (beta)APP is an integral transmembrane glycoprotein whose
cellular function is unknown. One of the processing pathways of (beta)APP
leads to the secretion of A(beta), the major constituent of the amyloid
deposited in the brain parenchyma and vessel walls of Alzheimer's disease
patients. We have found that the X11 PI domain binds a YENPTY motif in the
intracellular domain of (beta)APP that is strikingly similar to the NPXY
motifs that bind the Shc and IRS-1 PI/PTB domains. However, unlike the case
for binding of the Shc PI/PTB domain, tyrosine phosphorylation of the
YENPTY motif is not required for the binding of (beta)APP to X11 or FE65.
The binding site of the FE65 PI domain appears to be different from that of
X11, as mutations within the YENPTY motif differentially affect the binding
of X11 and FE65. Using site-directed mutagenesis, we have identified a
crucial residue within the PI domain involved in X11 and FE65 binding to
(beta)APP. The binding of X11 or FE65 PI domains to residues of the YENPTY
motif of (beta)APP identifies PI domains as general protein interaction
domains and may have important implications for the processing of
(beta)APP.
Copyright © 1996, American Society for Microbiology
The phosphotyrosine interaction domains of X11 and FE65 bind to distinct sites on the YENPTY motif of amyloid precursor protein
Howard Hughes Medical Institute, University of Michigan Medical School, Ann Arbor 48109, USA.
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