The gamma interferon (IFN-γ)-activated inhibitor of translation (GAIT) complex 
in human myeloid cells is heterotetrameric, consisting of glutamyl-prolyl-tRNA 
synthetase (EPRS), NS1-associated protein 1 (NSAP1), ribosomal protein L13a, and 
glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The complex binds a structural 
GAIT element in the 3' untranslated region of VEGF-A and other 
inflammation-related transcripts and inhibits their translation. EPRS is dually 
phosphorylated by cyclin-dependent kinase 5 (Cdk5) at Ser(886) and then by a 
Cdk5-dependent-AGC kinase at Ser(999); L13a is phosphorylated at Ser(77) by 
death-associated protein kinases DAPK and ZIPK. Because profound differences in 
inflammatory responses between mice and humans are known, we investigated the 
GAIT system in mouse macrophages. The murine GAIT complex is heterotrimeric, 
lacking NSAP1. As in humans, IFN-γ activates the mouse macrophage GAIT system 
via induced phosphorylation of EPRS and L13a. Murine L13a is phosphorylated at 
Ser(77) by the DAPK-ZIPK cascade, but EPRS is phosphorylated only at Ser(999). 
Loss of EPRS Ser(886) phosphorylation prevents NSAP1 incorporation into the GAIT 
complex. However, the triad of Ser(999)-phosphorylated EPRS, 
Ser(77)-phosphorylated L13a, and GAPDH forms a functional GAIT complex that 
inhibits translation of GAIT target mRNAs. Thus, translational control by the 
heterotrimeric GAIT complex in mice exemplifies the distinctive species-specific 
responses of myeloid cells to inflammatory stimuli.