Figure 1. Lyn A and Lyn B isoforms and their expression in Lyn-null mast cells.
(A) Schematic representation of Lyn isoforms with the sequence of the 21 amino acid insert found in Lyn A, but not in Lyn B, indicated. (B) Protein expression of Lyn A and Lyn B relative to wild type (WT) mast cells. (C) Analysis of FcεRI expression on cells transduced with lentiviral constructs of Lyn A and Lyn B after blasticidin selection and cell differentiation (5 weeks) in IL-3 and SCF. (D) Activity of Lyn A and Lyn B as measured by in vitro kinase assays (autophosphorylation). The activity of Lyn A and Lyn B isoforms is not impaired by their individual expression and is regulated by ATP. (E) Immunoblot of the phosphorylation status of the activation loop Y396 (using an antibody to human Lyn Y416) and of inhibitory Y507 on Lyn A and Lyn B isoforms, upon FcεRI stimulation. Graph shows the ratio of Y396/Y507 for both isoforms. (B–E) A representative experiment is shown.