Updated project metadata. IFITM proteins play a role in cancer cell progression through undefined mechanisms. Recent data demonstrated that interferon induced transmembrane 1 and 3 (IFITM1/3) proteins are required for the interferon gamma (IFNγ) stimulated synthesis of a subset of IFN-stimulated proteins; including human leukocyte antigen B (HLA-B). SBP-tagged IFITM1 protein was used to identify an association of IFITM1 protein with the cytosolic isoform of serine and arginine rich splicing factor 1 (SRSF1). This cytosolic association was confirmed in situ using proximity ligation assays for SRSF1 and IFITM1/3 suggesting a role associated with translation. Accordingly, IFITM1/3 were shown to interact with HLA-B mRNA in response to IFNγ stimulation using RNA-protein proximity ligation assays. In addition, shotgun RNA sequencing in IFITM1/IFITM3 null cells and wt-SiHa cells indicated that reduced HLA-B gene expression does not account for lowered HLA-B protein synthesis in response to IFNγ. Furthermore, ribosome profiling by using sucrose gradient sedimentation identified a reduction in 80S ribosomal fraction an IFITM1/IFITM3 null cells compared to their wild-type counterpart, partially reverted by IFITM1/3 complementation. Taking all together, these data link the binding of IFITM1/3 proteins to HLA-B mRNA and SRSF1 as a mechanism to catalyze the synthesis of target proteins suggesting an RNA chaperonin role for IFITM1/3 proteins.