The amino acid sequences of the carboxyl termini of human and mouse hepatic lipase influence cell surface association

被引:11
作者
Brown, RJ
Schultz, JR
Ko, KWS
Hill, JS
Ramsamy, TA
White, AL
Sparks, DL
Yao, ZM
机构
[1] Univ Ottawa, Inst Heart, Lipoprot & Atherosclerosis Res Grp, Ottawa, ON, Canada
[2] Univ Ottawa, Dept Biochem Microbiol & Immunol, Ottawa, ON, Canada
[3] Univ Ottawa, Dept Pathol & Lab Med, Ottawa, ON, Canada
[4] Univ British Columbia, Dept Pathol & Lab Med, Vancouver, BC, Canada
[5] Univ Texas, SW Med Ctr, Dept Clin Nutr, Dallas, TX 75390 USA
关键词
lipolysis; heparin; heparin binding domain; heparan sulfate proteoglycan; tributyrin; triolein; HIGH-DENSITY-LIPOPROTEINS; RECEPTOR-RELATED PROTEIN; TRIGLYCERIDE LIPASE; TRIACYLGLYCEROL LIPASE; CHIMERIC LIPASE; BINDING-SITES; CDNA SEQUENCE; BETA-VLDL; RAT-LIVER; HEPARIN;
D O I
10.1194/jlr.M200374-JLR200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Human hepatic lipase (hHL) mainly exists cell surface bound, whereas mouse HL (mHL) circulates in the blood stream. Studies have suggested that the carboxyl terminus of HL mediates cell surface binding. We prepared recombinant hHL, mHL, and chimeric proteins (hHLmt and mHLht) in which the carboxyl terminal 70 amino acids of hHL were exchanged with the corresponding sequence from mHL. The hHL, mHL, and hHLmt proteins were catalytically active using triolein and tributyrin as substrates. In transfected cells, the majority of hHLs bound to the cell surface, with only 4% of total extracellular hHL released into heparin-free media, whereas under the same conditions, 61% of total extracellular mHLs were released. Like mHL, hHLmt showed decreased cell surface binding, with 68% of total extracellular hHLmt released. To determine the precise amino acid residues involved in cell surface binding, we prepared a truncated hHL mutant (hHL(471)) by deleting the carboxyl terminal five residues (KRKIR). The hHL(471) also retained hydrolytic activity with triolein and tributyrin, and showed decreased cell surface binding, with 40% of total extracellular protein released into the heparin-free media. These data suggest that the determinants of cell surface binding exist within the carboxyl terminal 70 amino acids of hHL, of which the last five residues play an important role.
引用
收藏
页码:1306 / 1314
页数:9
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