Identification of calnexin as a binding protein for Amadori-modified glycated albumin.
Albumin modified by Amadori glucose adducts (glycated albumin) selectively binds to glomerular mesangial cells and triggers signal transduction processes that modulate cellular function. To identify glycated albumin binding proteins, we applied membrane extracts prepared from murine mesangial cells to a column of lysine-Sepharose followed by application to an affinity column of fructosyllysine-Sepharose. This procedure yielded an approximately 90 kDa polypeptide that immunoreacted with Amadori-modified but not carbohydrate-free albumin. MALDI mass fingerprinting matched 9 out of 25 peptides with calnexin, and amino acid analysis showed homology with this transmembrane calcium-binding protein of the calreticulin family. These results indicate that one of the mesangial cell receptors for glycated albumin is a calnexin-like protein.
Wu
V Y
VY
Institute of Metabolic Research, University City Science Center, Philadelphia, Pennsylvania 19104, USA.
Shearman
C W
CW
Cohen
M P
MP
D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D037281:Calnexin; D002478:Cells, Cultured; D005920:Glomerular Mesangium / Q000378:metabolism; D017127:Glycation End Products, Advanced; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D051379:Mice; D012709:Serum Albumin / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000093423:Glycated Serum Albumin
D002135:Calcium-Binding Proteins; D017127:Glycation End Products, Advanced; D012709:Serum Albumin; D037281:Calnexin; C033186:fructosyl-lysine; D008239:Lysine; D000093423:Glycated Serum Albumin