NTAL/LAB/LAT2
Abstract
NTAL (non-T cell activation linker)/LAB (linker for activation of B cells), now officially termed LAT2 (linker for activation of T cells 2) is a 25-30 kD transmembrane adaptor protein (TRAP) associated with glycolipid-enriched membrane fractions (GEMs; lipid raft) in specific cell types of hematopoietic lineage. Tyrosine phosphorylation of NTAL/LAB/LAT2 is induced by FcεRI aggregation and Kit dimerization in mast cells, FcγRI aggregation in monocytes, and BCR aggregation in B cells. NTAL/LAB/LAT2 is also expressed in resting NK cells but, unlike the related TRAP, LAT, not in resting T cells. As demonstrated in monocytes and B cells, phosphorylated NTAL/LAB/LAT2 recruits signaling molecules such as Grb2, Gab1 and c-Cbl into receptor-signaling complexes. Although gene knock out and knock down studies have indicated that NTAL/LAB/LAT2 may function as both a positive and negative regulator of mast cell activation, its precise role in the activation of these and other hematopoietic cells remains enigmatic.
Footnotes
Work in the authors' laboratory is supported by the NIAID Intramural Program within the National Institutes of Health and a Japan Society for the Promotion of Science research fellowship for Japanese Biomedical and Behavioral Research at National Institutes of Health to S. Iwaki.
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