Supplemental Figure S1
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Fig. S1. tTG does not interact with the β chain of LRP1. Myc-tagged LRP1 β chain (LRPβ) or truncated LRP1 β chain with a deletion of the cytoplasmic tail (LRPβΔCT) were transiently expressed in wild-type CHO cells (CHO wt) and LRP1-deficient CHO 13-5-1 cells. The transfectants were tested by immunoblotting for expression of exogenous LRPβ and LRPβΔCT with a mAb against Myc. Alternatively, expression levels of endogenous LRPβ and exogenous proteins were compared by immunoblotting with mAb 5A6, which reacts with the extracellular portion of the LRP β chain. Note the overexpression of exogenous LRPβ or LRPβΔCT compared with endogenous LRPβ. In parallel, cell extracts were subjected to immunoprecipitation with mAb 5A6, followed by detection of tTG in the LRP1 immune complexes or in whole-cell lysates. Overexpression of LRPβ or LRPβΔCT did not increase the amounts of tTG in the LRP1 immune complexes isolated from CHO wt transfectants (left lower panel). As expected, no association of tTG with LRPβ or LRPβΔCT was detected in the CHO 13-5-1 transfectants (right lower panel). These data implicate the α chain of LRP1 in the association with tTG.
