Structural requirements for intracellular processing and sorting of bactericidal/permeability-increasing protein (BPI): comparison with lipopolysaccharide-binding protein

Journal of Leukocyte Biology

Elinor Bülow¹  Inge Olsson¹  Urban Gullberg¹ 

[1] Department of Hematology, Research Department 2, University Hospital, Lund, SwedenDepartment of Hematology, Research Department 2, University Hospital, Lund, SwedenDepartment of Hematology, Research Department 2, University Hospital, Lund, Sweden

关键词: azurophil granule;    chimera;    neutrophil;    secretion;    stability;   

DOI  :  

学科分类：生理学

来源: Federation of American Societies for Experimental Biology

【 摘 要 】

The bactericidal/permeability-increasing protein (BPI), which is stored in the azurophil granules of neutrophils, and the circulating lipopolysaccharide-binding protein (LBP) share the same structure. Both bind lipopolysaccharide of gram-negative bacteria through their amino-terminal domains. The carboxy-terminal domain of BPI promotes bacterial attachment to phagocytes, whereas the corresponding domain of LBP delivers lipopolysaccharide to monocytes/macrophages. Our aim was to investigate the role of the amino- and carboxy-terminal domains of BPI and LBP for sorting and storage in myeloid cells after transfection of cDNA to two rodent hematopoietic cell lines. Full-length BPI and LBP were both targeted for storage in these cells. Deletion of the carboxy-terminal half of BPI resulted in storage followed by degradation while the reciprocal deletion of the amino-terminal half led to retention in the endoplasmic reticulum for proteasomal degradation. Chimeras between halves of BPI and LBP were also targeted for storage, but those containing carboxy-terminal BPI had the highest stability, again indicating a role for the carboxy-terminal domain of BPI in protection against degradation. Therefore, we propose a critical stability function for the hydrophobic carboxy-terminal domain of BPI during intracellular sorting for storage while the amino-terminal domain may confer targeting for storage.

【 授权许可】

Unknown