Journal of Biological Chemistry
Volume 276, Issue 38, 21 September 2001, Pages 35778-35785
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MEMBRANE TRANSPORT STRUCTURE FUNCTION AND BIOGENESIS
Structural and Functional Characterization of Protein 4.1R-Phosphatidylserine Interaction: POTENTIAL ROLE IN 4.1R SORTING WITHIN CELLS*

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Erythrocyte protein 4.1R is a multifunctional protein that binds to various membrane proteins and to phosphatidylserine. In the present study, we report two important observations concerning 4.1R-phosphatidylserine interaction. Biochemically, a major finding of the present study is that 4.1R binding to phosphatidylserine appears to be a two-step process in which 4.1R first interacts with serine head group of phosphatidylserine through the positively charged amino acids YKRS and subsequently forms a tight hydrophobic interaction with fatty acid moieties. 4.1R failed to dissociate from phosphatidylserine liposomes under high ionic strength but could be released specifically by phospholipase A2 but not by phospholipase C or D. Biochemical analyses showed that acyl chains were associated with 4.1R released by phospholipase A2. Importantly, the association of acyl chains with 4.1R impaired its ability to interact with calmodulin, band 3, and glycophorin C. Removal of acyl chains restored 4.1R binding. These data indicate that acyl chains of phosphatidylserine play an important role in its interaction with 4.1R and on 4.1R function. In terms of biological significance, we have obtained evidence that 4.1R-phosphatidylserine interaction may play an important role in cellular sorting of 4.1R.

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Published, JBC Papers in Press, June 22, 2001, DOI 10.1074/jbc.M101364200

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This work was supported in part by Grants-in aid for Scientific Research 10877022 and 10671388 from the Ministry of Education of Japan and by National Institutes of Health Grants DK 26263, DK 32094, and DK 56355.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.