Evidence for carbohydrate recognition and homotypic and heterotypic binding by the TIM family

PR Wilker, JR Sedy, V Grigura, TL Murphy… - International …, 2007 - academic.oup.com
PR Wilker, JR Sedy, V Grigura, TL Murphy, KM Murphy
International immunology, 2007academic.oup.com
The T cell Ig domain and mucin domain (TIM) proteins form a conserved family of
transmembrane cell-surface glycoproteins expressed by a variety of tissues. Each TIM
protein contains a single V-type Ig domain, a glycosylated mucin-like domain, a
transmembrane domain and a cytoplasmic domain. TIM proteins recognize a diverse array
of ligands, including H-ferritin, galectin-9 as well as other TIM family members. In this study,
we demonstrate that the Ig domains of murine TIM-1,-3 and-4 display calcium-dependent …
Abstract
The T cell Ig domain and mucin domain (TIM) proteins form a conserved family of transmembrane cell-surface glycoproteins expressed by a variety of tissues. Each TIM protein contains a single V-type Ig domain, a glycosylated mucin-like domain, a transmembrane domain and a cytoplasmic domain. TIM proteins recognize a diverse array of ligands, including H-ferritin, galectin-9 as well as other TIM family members. In this study, we demonstrate that the Ig domains of murine TIM-1, -3 and -4 display calcium-dependent binding to ligands expressed by murine splenocytes and several non-murine cell lines, indicating non-species-specific ligand recognition. Further, the intrafamilial interaction of various TIM family Ig domains with surface-expressed TIM-1 and TIM-4 requires an intact TIM-1 and TIM-4 glycosylated mucin stalk. Importantly, we also uncovered the previously unrecognized potential for homotypic TIM interactions in forming ligand–receptor pairs. Using a glycan array screen, we identified the novel capacity of the TIM-3 Ig domain to recognize specific carbohydrate moieties, suggesting a role for carbohydrate modification along with protein epitopes in TIM ligand recognition. Identification of the carbohydrate-binding capacity of TIM proteins helps explain the diversity of ligands recognized by this family and adds to our understanding of homotypic and heterotypic interactions between TIM family members.
Oxford University Press