Extended Data Fig. 7: Identification of MERTK as a receptor of feimin.
From: A feeding-induced myokine modulates glucose homeostasis
a-c, Immunoblots showing knockout of Mertk (a), Axl (b) or Tyro3 (c) in mice. The red arrows indicate the respective proteins. d-e, Immunostaining showing the effect of Axl knockout (d) or Tyro3 knockout (e) on feimin binding to frozen mouse tissue sections. 100 nM GST-feimin was incubated with frozen tissue slices. Scale bars, 20 μm. f, Coomassie staining showing SDS-PAGE separation of purified human GAS6, mouse feimin, MERTK (1-484 aa) and its mutant (Mut, E396R, D402R, D414R, E416R, E434R, E437R, E438R, D474R), AXL (1-428 aa) and TYRO3 (1-416 aa). Ex, the extracellular domain. g, Typical MST binding experiments showing the affinity between feimin and the extracellular domain (Ex) of AXL (1-428 aa) or TYRO3 (1-416 aa). Data are shown as mean ± s.e.m. n = 3 biological replicates. h, Deletion analysis to identify the regions in MERTK required for the feimin-MERTK interaction. Interaction-competent MERTK polypeptides are indicated by (+) in each schematic. IG, immunoglobulin-like domain; FNIII, fibronectin type III domain; TM, transmembrane domain; TK, tyrosine kinase domain. i-j, Alignment of the second FNIII domain of MERTK from different species (i) and protein structure of human MERTK (j) from AlphaFold. The positions of mutated amino acids are shown by the red arrows (i and j, right panel). k, GST pulldown assay showing the interaction between GST-feimin and MERTK-Flag or its mutant (Mut, E396R, D402R, D414R, E416R, E434R, E437R, E438R, D474R) in HEK293T cells. l, Typical MST binding experiments showing the affinity between GAS6 and the extracellular domain (Ex) of MERTK (1-484 aa) or its mutant (Mut, E396R, D402R, D414R, E416R, E434R, E437R, E438R, D474R). Data are shown as mean ± s.e.m. n = 3 biological replicates.
