The number of different conformations of the N TAIL deletion proteins is limited, as indicated by the sharpness of the peaks observed in gel filtration (data not shown). As expected for intrinsically disordered protein subdomains, the Stokes radius (R S ) values, as inferred by gel filtration (27 6 3 Å , 22 6 3 Å , and 27 6 3 Å for N TAILD3 , N TAILD2,3 , and N TAILD1 , respectively), are consistent with extended conformations (see Materials and Methods). Thus, these deletion proteins share similar hydrodynamic properties with full-length N TAIL , all possessing an elongated shape.