Endogenous cleavage of annexin I generates a truncated protein with a reduced calcium requirement for binding to neutrophil secretory vesicles and plasma membrane.
We have earlier shown that an N-terminal truncated annexin I molecule, annexin I(des1-8), is generated in human neutrophils through cleavage by a membrane localized metalloprotease. The truncated protein showed differences in membrane binding among the neutrophil granule populations as compared to full-length annexin I. In this study, we investigated the cleavage capabilities of isolated neutrophil secretory vesicles and plasma membrane, and the binding of full-length annexin I and annexin I(des1-8) to these membrane fractions. Translocations were performed in vitro to secretory vesicles and plasma membrane, respectively, at different Ca(2+) concentrations. We show that the annexin I-cleaving membrane localized metalloprotease is present both in the secretory vesicles and the plasma membrane. The N-terminal truncation of annexin I gives rise to a molecule with a decreased Ca(2+) requirement for binding, both to secretory vesicles and plasma membrane. There was, thus, no difference in binding of either full-length annexin I or annexin I(des1-8) to the secretory vesicles as compared to the plasma membrane.
Movitz
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The Phagocyte Research Laboratory, Department of Medical Microbiology and Immunology, Box 435, Göteborg University, S-413 46, Göteborg, Sweden. charlotta. movitz@microbio.gu.se
Dahlgren
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D017305:Annexin A1 / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004229:Dithiothreitol; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D006801:Humans; D015151:Immunoblotting; D009504:Neutrophils / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D022142:Secretory Vesicles / Q000201:enzymology / Q000378:metabolism
D017305:Annexin A1; D011506:Proteins; D010450:Endopeptidases; D002118:Calcium; D004229:Dithiothreitol