Skip to main content
Journal cover image

Ligation of the alpha 2-macroglobulin signalling receptor on macrophages induces protein phosphorylation and an increase in cytosolic pH.

Publication ,  Journal Article
Misra, UK; Gawdi, G; Pizzo, SV
Published in: Biochem J
July 1, 1995

We have recently described an alpha 2-macroglobulin (alpha 2M) signalling receptor which is distinct from the low-density lipoprotein-related protein/alpha 2M receptor (LRP/alpha 2MR). Ligation of the macrophage signalling receptor by alpha 2M-methylamine stimulates production of several second messengers and involves a pertussis toxin-insensitive G-protein. We now report that binding of alpha 2M-methylamine, or the cloned M(r) = 20,000 receptor-binding fragment from rat alpha 1M, to macrophage alpha 2M signalling receptors induces protein phosphorylation. By use of a monoclonal antibody to phospholipase C gamma l (PLC gamma l) we were able to identify it as one target for protein phosphorylation. Phosphorylation was time and concentration dependent, being optimal at about 60 s of incubation and a 100-200 nM ligand concentration. By use of a second monoclonal antibody directed against phosphotyrosine, we were able to demonstrate that at least a portion of the label was incorporated into one or more tyrosine residues. PLC gamma l phosphorylation was then studied in membrane preparations at 4 degrees C in order to minimize serine or threonine modification. Preincubation of macrophage membranes with genistein, a tyrosine kinase inhibitor, drastically reduced phosphorylation of PLC gamma l. Receptor-associated protein, which blocks alpha 2M binding to LRP/alpha 2MR but not to the alpha 2M signalling receptor, had no effect on alpha 2M-methylamine-induced tyrosine phosphorylation of PLC gamma l. Binding of lactoferrin to LRP/alpha 2MR failed to induce phosphorylation of PLC gamma l, further supporting the hypothesis that the alpha 2M signalling receptor and LRP/alpha 2MR are distinct entities. Growth factors which induce tyrosine phosphorylation typically cause a rise in cytosolic pH. Binding of a2M-methylamine to macrophages also gradually increased the intracellular pH in a concentration-dependent manner, being optimal at a 200 nM ligand concentration. The increase in pH was amiloride sensitive. We propose that receptor-recognized forms of a2M may function like growth factors with regard to macrophage regulation.

Duke Scholars

Published In

Biochem J

DOI

ISSN

0264-6021

Publication Date

July 1, 1995

Volume

309 ( Pt 1)

Issue

Pt 1

Start / End Page

151 / 158

Location

England

Related Subject Headings

  • alpha-Macroglobulins
  • Tyrosine
  • Type C Phospholipases
  • Receptors, Immunologic
  • Rats
  • Phosphorylation
  • Phospholipase C gamma
  • Mice, Inbred C57BL
  • Mice
  • Macrophages
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Misra, U. K., Gawdi, G., & Pizzo, S. V. (1995). Ligation of the alpha 2-macroglobulin signalling receptor on macrophages induces protein phosphorylation and an increase in cytosolic pH. Biochem J, 309 ( Pt 1)(Pt 1), 151–158. https://doi.org/10.1042/bj3090151
Misra, U. K., G. Gawdi, and S. V. Pizzo. “Ligation of the alpha 2-macroglobulin signalling receptor on macrophages induces protein phosphorylation and an increase in cytosolic pH.Biochem J 309 ( Pt 1), no. Pt 1 (July 1, 1995): 151–58. https://doi.org/10.1042/bj3090151.
Misra, U. K., et al. “Ligation of the alpha 2-macroglobulin signalling receptor on macrophages induces protein phosphorylation and an increase in cytosolic pH.Biochem J, vol. 309 ( Pt 1), no. Pt 1, July 1995, pp. 151–58. Pubmed, doi:10.1042/bj3090151.
Journal cover image

Published In

Biochem J

DOI

ISSN

0264-6021

Publication Date

July 1, 1995

Volume

309 ( Pt 1)

Issue

Pt 1

Start / End Page

151 / 158

Location

England

Related Subject Headings

  • alpha-Macroglobulins
  • Tyrosine
  • Type C Phospholipases
  • Receptors, Immunologic
  • Rats
  • Phosphorylation
  • Phospholipase C gamma
  • Mice, Inbred C57BL
  • Mice
  • Macrophages