Mouse Immunoglobulin Subclasses: Cyanogen Bromide Fragments and Partial Sequence of a γ1 Chain

Abstract

The purification and characterisation of all the cyanogen bromide fragments of MOPC 21 heavy (γ1) chain is described. The ten BrCN fragments account for the whole chain. Four of these fragments have been used to establish the sequence of the C‐terminal stretch (138 residues) that includes the entire CH3 and a part of the CH2 homology regions. A comparison of this sequence with homologous sequences is presented. Mouse γ1 and γ2 proteins differ much more than the γ subclasses in humans and in other species. The comparison further suggests that the four human γ subclasses and mouse γ1 have a common ancestor which differs from the mouse γ2 ancestor. Unlike other subclasses, mouse γ1 and γ2 genes have diverged before speciation. Copyright © 1975, Wiley Blackwell. All rights reserved