Identification of cytokeratin 1 as a binding protein and presentation receptor for kininogens on endothelial cells.
A kininogen binding protein(s), a putative receptor, was identified on endothelial cells. A 54-kDa protein was isolated by a biotin-high molecular mass kininogen (HK) affinity column that, on aminoterminal sequencing of tryptic digests, was identified as cytokeratin 1. Multiple antibodies directed to cytokeratin 1 reacted with a 54-kDa band on immunoblot of lysates of endothelial cells. On laser scanning confocal microscopy, cytokeratin 1 antigen was found on the surface of endothelial cells. Cytokeratin 1 antigen also was detected on endothelial cell membranes by flow cytometry. Moreover, an antipeptide antibody to a sequence unique to cytokeratin 1 also specifically bound to nonpermeabilized endothelial cells. Biotin-HK specifically bound to cytokeratin only in the presence of Zn2+, and cytokeratin blocked biotin-HK binding to endothelial cells. Further, HK and low molecular mass kininogen, but not factor XII, blocked biotin-HK binding to cytokeratin, and peptides of each cell binding region of HK on domains 3,4, and 5 blocked biotin-HK binding to cytokeratin. gC1qR and soluble urokinase-like plasminogen activator receptor also inhibited biotin-HK binding to cytokeratin. These investigations identify a new function for cytokeratin 1 as a kininogen binding protein. Cytokeratins, members of the family of intermediate filament proteins, may represent a new class of receptors.
Hasan
A A
AA
Hematology/Onclogy Division, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0640, USA.
Zisman
T
T
Schmaier
A H
AH
D004730:Endothelium, Vascular / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007633:Keratins / Q000032:analysis / Q000378:metabolism*; D007704:Kininogens / Q000378:metabolism*; D018613:Microscopy, Confocal; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism*
D007704:Kininogens; D011956:Receptors, Cell Surface; D007633:Keratins