Figure S1.

RAG1 protein and mRNA expression in WT and RAG1 mutant mice. (A) Sequencing tracks of PCR products amplified from the genomes of RAG1 NTR mutant mice. Red boxes indicate site of indicated mutation. Single asterisk indicates K234 and L235, where silent mutations were introduced to disrupt PAM site in R1.KR mice. Double asterisks indicate R243 and R244, where silent mutations were introduced to add a site for HindIII for genotyping purposes. The red asterisk indicates a passenger V238A mutation in R1.PG mice. This mutation is conservative, and V238 is not highly conserved and is replaced by alanine or isoleucine in several jawed vertebrates (Fig. S4 B from Brecht et al., 2020). It is not predicted to have an impact on RAG activity. (B) Western blot of RAG1 in whole thymic lysates from additional independent WT and RAG1 mutant mice. Open triangles, full-length protein; closed triangles, truncated proteins. (C) RAG1 mRNA expression in whole thymic lysates from mice of indicated genotypes, calculated relative to that of HPRT. Each dot indicates data from an independent mouse, with data presented as mean ± SEM. Statistical significance determined by two-tailed unpaired t tests (ns, P > 0.05; * P, ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001).