Isolation and structural characterization of a Zn2+-bound single-domain antibody against NorC, a putative multi-drug efflux transporter in bacteria — Zn2+-bound camelid antibody that binds an efflux transporter — Isolation and structural characterization of a Zn2+-bound single-domain antibody against NorC, a putative multidrug efflux transporter in bacteria — Zn2+-bound camelid antibody that binds an efflux transporter