title: Interaction between platelet glycoprotein Ibalpha and filamin-1 is essential for glycoprotein Ib/IX receptor anchorage at high shear.
abstract: The interaction of the glycoprotein (GP) Ib-V-IX receptor complex with the membrane skeleton of platelets is dependent on a specific interaction between the cytoplasmic tail of GPIbalpha and filamin-1. This interaction has been proposed to regulate key aspects of platelet function, including the ligand binding of GPIb-V-IX and the ability of the cells to sustain adhesion to von Willebrand factor (vWf) under high shear. In this study we have examined sequences in the GPIbalpha intracellular domain necessary for interaction of the receptor with filamin-1. We have identified two adjacent sequences involving amino acids 557-568 and 569-579 of the GPIbalpha cytoplasmic domain that are critical for normal association between the receptor complex and filamin-1. Under flow conditions, Chinese hamster ovary (CHO) cells expressing these two mutant receptors exhibited an increase in translocation velocity that was associated with increased cell detachment from the vWf matrix at high shear. The shear-dependent acceleration in velocity of mutant Delta557-568 and Delta569-579 CHO cells was associated with a critical defect in receptor anchorage, evident from significant extraction of GPIb-IX from the CHO cell membrane at high shear. These studies define a critical role for amino acids within the 557-579 sequence of GPIbalpha for interaction with filamin-1.
authors.affiliation: Australian Centre for Blood Diseases, Department of Medicine, Monash University, Box Hill Hospital, Victoria 3128, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Williamson
authors.forename: Inna
authors.initials: I
authors.lastname: Pikovski
authors.forename: Susan L
authors.initials: SL
authors.lastname: Cranmer
authors.forename: Pierre
authors.initials: P
authors.lastname: Mangin
authors.forename: Nayna
authors.initials: N
authors.lastname: Mistry
authors.forename: Teresa
authors.initials: T
authors.lastname: Domagala
authors.forename: Sam
authors.initials: S
authors.lastname: Chehab
authors.forename: Francois
authors.initials: F
authors.lastname: Lanza
authors.forename: Hatem H
authors.initials: HH
authors.lastname: Salem
authors.forename: Shaun P
authors.initials: SP
authors.lastname: Jackson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D003285:Contractile Proteins / Q000378:metabolism*; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism; D017931:DNA Primers; D064448:Filamins; D008840:Microfilament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017384:Sequence Deletion
chemical_list: D003285:Contractile Proteins; D017931:DNA Primers; D064448:Filamins; D008840:Microfilament Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex