Structural and functional consequences of tyrosine phosphorylation in the LRP1 cytoplasmic domain.
The cytoplasmic domain of LRP1 contains two NPXY motifs that have been shown to interact with signaling proteins. In previous work, we showed that Tyr(4507) in the distal NPXY motif is phosphorylated by v-Src, whereas denaturation of the protein was required for phosphorylation of Tyr(4473) in the membraneproximal NPXY motif. Amide H/D exchange studies reveal that the distal NPXY motif is fully solvent-exposed, whereas the proximal one is not. Phosphopeptide mapping combined with in vitro and in vivo kinase experiments show that Tyr(4473) can be phosphorylated, but only if Tyr(4507) is phosphorylated or substituted with glutamic acid. Amide H/D exchange experiments indicate that solvent accessibility increases across the entire LRP1 cytoplasmic region upon phosphorylation at Tyr(4507); in particular the NPXY(4473) motif becomes much more exposed. This differential phosphorylation is functionally relevant: binding of Snx17, which is known to bind at the proximal NPXY motif, is inhibited by phosphorylation at Tyr(4473). Conversely, Shp2 binds most strongly when both of the NPXY motifs in LRP1 are phosphorylated.
Betts
Gina N
GN
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0378, USA.
van der Geer
Peter
P
Komives
Elizabeth A
EA
D020816:Amino Acid Motifs / Q000502:physiology; D006801:Humans; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015688:Oncogene Protein pp60(v-src) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping / Q000379:methods; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D058305:Sorting Nexins; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D026503:Low Density Lipoprotein Receptor-Related Protein-1; C487895:SNX17 protein, human; D058305:Sorting Nexins; D033921:Vesicular Transport Proteins; D014443:Tyrosine; D015688:Oncogene Protein pp60(v-src); D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11