Fig. 1

Nanobodies specific for yeast SUMO (Smt3p) protein and their binding characteristics. (A) Anti-Smt3p nanobody sequences with their complementarity determining regions (CDRs) indicated, based on IMGT database³⁸. The sequence identity for CDR3 in VHH2-4_SMT3 suggests a common progenitor, with accumulation of several somatic mutations in its descendants. Using the VHH2_SMT3 sequence as the basis for comparison, these somatic mutations are color-coded blue in VHHs 2-4_SMT3. (B) Binding of nanobodies to His6- Smt3p as determined by size exclusion chromatography (SEC). Profiles of His6-Smt3p (Blue), VHHs (Green), and an equimolar mixture of Smt3p:VHH (red) are shown. The fractions corresponding to the VHH:Smt3p complex (red peak) were analyzed by SDS PAGE and Native PAGE, as indicated.