title: L-selectin transmembrane and cytoplasmic domains are monomeric in membranes.
abstract: A recombinant protein termed CLS, which corresponds to the C-terminal portion of human L-selectin and contains its entire transmembrane and cytoplasmic domains (residues Ser473-Arg542), has been produced and its oligomeric state in detergents characterized. CLS migrates in the SDS polyacrylamide gel at a pace that is typically expected from a complex twice of its molecular weight. Additional studies revealed, however, that this is due to residues in the cytoplasmic domain, as mutations in this region or its deletion significantly increased the electrophoretic rate of CLS. Analytical ultracentrifugation and fluorescence resonance energy transfer studies indicated that CLS reconstituted in dodecylphosphocholine detergent micelles is monomeric. When the transmembrane domain of L-selectin is inserted into the inner membrane of Escherichia coli as a part of a chimeric protein in the TOXCAT assay, little oligomerization of the chimeric protein is observed. Overall, these results suggest that transmembrane and cytoplasmic domains of L-selectin lack the propensity to self-associate in membranes, in contrast to the previously documented dimerization of the transmembrane domain of closely related P-selectin. This study will provide constraints for future investigations on the interaction of L-selectin and its associating proteins.
authors.affiliation: Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
authors.forename: Sankaranarayanan
authors.initials: S
authors.lastname: Srinivasan
authors.forename: Wei
authors.initials: W
authors.lastname: Deng
authors.forename: Renhao
authors.initials: R
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D019041:L-Selectin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010455:Peptides; D011994:Recombinant Proteins; D010767:Phosphorylcholine; D019041:L-Selectin; C028810:dodecylphosphocholine