Characterization of alpha 2-macroglobulin binding to human trabecular meshwork cells: presence of the alpha 2-macroglobulin signaling receptor.

Journal Article (Journal Article)

Direct binding of receptor-recognized alpha 2-macroglobulin (alpha 2M*) or a cloned receptor binding fragment from rat alpha 1-macroglobulin (RBF) to human trabecular meshwork cells demonstrated two classes of cell surface binding sites. One class has an apparent Kd of 5.0 nM and a receptor number of 31,800 receptors/cell. The other class has an apparent Kd of 20 pM and a receptor number of 1600 receptors/cell. Binding studies of alpha 2M* or RBF in the presence of a competitor for binding to low-density-lipoprotein receptor-related protein/alpha 2M* receptor (LRP/alpha 2MR) called receptor-associated protein (RAP) show that only the lower affinity class of binding sites is susceptible to competition with RAP. Uptake studies demonstrate specific internalization and degradation of alpha 2M* which is inhibitable by RAP. Exposure of the cells to alpha 2M* and RBF (40 nM) is associated with mean increases of 171 and 210%, respectively, in the intracellular calcium concentration, which is not inhibitable by RAP or pertussis toxin. These studies present the first characterization of alpha 2M* and RBF signaling in a primary human cell type and suggest a role for alpha 2M* in the physiology of the eye.

Full Text

Duke Authors

Cited Authors

  • Howard, GC; Roberts, BC; Epstein, DL; Pizzo, SV

Published Date

  • September 1, 1996

Published In

Volume / Issue

  • 333 / 1

Start / End Page

  • 19 - 26

PubMed ID

  • 8806749

International Standard Serial Number (ISSN)

  • 0003-9861

Digital Object Identifier (DOI)

  • 10.1006/abbi.1996.0359


  • eng

Conference Location

  • United States