The CEACAM1 N-terminal Ig domain mediates cis- and trans-binding and is essential for allosteric rearrangements of CEACAM1 microclusters

Klaile, Esther; Vorontsova, Olga; Sigmundsson, Kristmundur; Müller, Mario M.; Singer, Bernhard B.; Öfverstedt, Lars-Göran; Svensson, Stina; Skoglund, Ulf; Öbrink, Björn

(1) formation of one class of dimers by one homophilic binding site (model 1); (2) formation of two classes of dimers (types 1 and 2) by two different homophilic binding sites (model 2); and (3) formation of two classes of dimers (types 1 and 2) and one class of trimers by two different homophilic binding sites (model 3). Formation of type 1 and type 2 dimers are characterized by a set of kinetic rate constants, k a1 /k d1 and k a2 /k d2 , respectively. Detailed reaction schemes and the derived equations are presented in Fig. S1 and Materials and methods. It should be emphasized that we apply a minimal number of parameters in these models and that the number of free-running parameters were the same in models 2 and 3.