A Quantitative Receptor Assay Using TRITON X-114 for Plasminogen Activator Binding Proteins in Solubilized Membranes from Human Liver and Placenta
✍ Scribed by G. Nguyen; E.K.O. Kruithof
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 427 KB
- Volume
- 208
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
Cell surface binding proteins play an important role in the localization of plasminogen activator (PA) activity at the cell surface or in the clearance of PAs. We describe a rapid and quantitative receptor assay applicable to the quantification and affinity determination of binding proteins for tissue-type PA and urokinasetype PA in solubilized membranes obtained from human liver, human placenta, or human monocyte-like cells. The method is based on the ability of a solution of the nonionic detergent Triton X-114 to phase separate at temperatures above (20^{\circ} \mathrm{C}). After incubation of integral membrane proteins with radiolabeled ligand, a solution of Triton (\mathrm{X}-114) is added at (4^{\circ} \mathrm{C}) and warmed to (37^{\circ} \mathrm{C}) to allow phase partitioning. Radiolabeled ligand bound to membrane protein is recovered in the detergent-rich lower phase which is separated by centrifugation from the detergent-poor upper phase containing free radiolabeled ligand. (c 1993) Academic Press, Inc.