uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Phosphorylation of complement component C3 and C3 fragments by a human platelet protein kinase. Inhibition of factor I-mediated cleavage of C3b.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
1995 (English)In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 154, no 12, 6502-6510 p.Article in journal (Refereed) Published
Abstract [en]

Phosphorylation of C3 in vitro has been shown previously to lead to significantly altered function of the protein. Platelets are known to contain and release considerable amounts of protein kinases and ATP, which are prerequisites for protein phosphorylation. The aim of the present study was to investigate whether C3 is phosphorylated extracellularly by human platelets. Platelet-rich plasma was stimulated by human aggregated gamma-globulin or ADP. The remaining cells were removed by centrifugation, and the plasma was incubated with [gamma-32P]ATP. After precipitation with Sepharose-bound Abs to C3c followed by SDS-PAGE, it was shown that C3 was phosphorylated in the alpha-chain by a protein kinase dependent on Mn2+, Ca2+, or Mg2+ ions. The supernatant from washed, activated platelets was incubated with purified C3 or soluble or activated thiol Sepharose-bound C3b, together with [gamma-32P]ATP. Phosphorylation was seen in the alpha-chain of C3, and to the same extent in the alpha'-chain of both C3b preparations. The analysis of acid hydrolysate demonstrated that C3 contained 32P-labeled Thr and 32P-labeled Ser. After extensive proteolysis with trypsin, the major phosphorylation site was located to a peptide of 3 to 4 kDa that was bound to the activated thiol Sepharose via the free sulphydryl group in the C3d fragment. Incubation of phosphorylated C3b with factors I and H showed that phosphorylation inhibited the cleavage of the alpha'-chain of C3b. The results in this study suggest that phosphorylation is a regulator of C3 during platelet activation induced, for example, by immune complexes.

Place, publisher, year, edition, pages
1995. Vol. 154, no 12, 6502-6510 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-266909PubMedID: 7539023OAI: oai:DiVA.org:uu-266909DiVA: diva2:869190
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01

Open Access in DiVA

No full text

PubMed
By organisation
Department of Oncology, Radiology and Clinical Immunology
In the same journal
Journal of Immunology
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

pubmed
urn-nbn

Altmetric score

pubmed
urn-nbn
Total: 276 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf