Major mutations in calf-1 and calf-2 domains of glycoprotein IIb in patients with Glanzmann thrombasthenia enable GPIIb/IIIa complex formation, but impair its transport from the endoplasmic reticulum to the Golgi apparatus

Nurit Rosenberg, Rivka Yatuv, Vladimir Sobolev, Hava Peretz, Ariella Zivelin, Uri Seligsohn*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

The crystal structure of integrin αv133 comprises 3 regions of contact between αv and β3. The main contact on αv is located in the β-propeller while calf-1 and calf-2 domains contribute minor interfaces. Whether or not contacts between calf-1 and calf-2 domains of glycoprotein (GP) IIb (αIIb) and GPIIIa (β3) play a role in GPIIb/IIIa complex formation has not been established. In this study we analyzed the effects of 2 naturally occurring mutations in calf-1 and calf-2 domains on GPIIb/IIIa complex formation, its processing, and transport to the cell membrane. The mutations investigated were a deletion-insertion in exon 25 located in calf-2 and an in-frame skipping of exon 20 located in calf-1. Mutated GPIIb cDNAs were co-transfected in baby hamster kidney cells with normal GPIIIa (β3) cDNA. Analysis by flow cytometry failed to demonstrate detectable amounts of GPIIb or GPIIb/IIIa complex on the surface of cells transfected with each mutation, but immunohistochemical staining revealed their intracellular presence. GPIIb was mainly demonstrable as pro-GPIIb by immunoprecipitation of cell lysates expressing each mutation. Differential immunofluorescence staining of GPIIb and cellular organelles suggested that most altered complexes were located in the endoplasmic reticulum. Homology modeling of normal GPIIb based on the αvβ3 crystal structure revealed similar contacts between αv and β3 and between αIIb and β3. Introduction of the mutations into the model yielded partial disruption of the normal contacts in the corresponding domains. These data suggest that despite partial disruption of calf-1 or calf-2 domain, GPIIb/IIIa complex is formed but its transport from the endoplasmic reticulum is impaired.

Original languageEnglish
Pages (from-to)4808-4815
Number of pages8
JournalBlood
Volume101
Issue number12
DOIs
StatePublished - 15 Jun 2003

Fingerprint

Dive into the research topics of 'Major mutations in calf-1 and calf-2 domains of glycoprotein IIb in patients with Glanzmann thrombasthenia enable GPIIb/IIIa complex formation, but impair its transport from the endoplasmic reticulum to the Golgi apparatus'. Together they form a unique fingerprint.

Cite this