Immunoglobulins homology regions

Homologous proteins have similar three-dimensional structures. They contain a core region, a scaffold of secondary structure elements, where the folds of the polypeptide chains are very similar. Loop regions that connect the building blocks of the scaffolds can vary considerably both in length and in structure. From a database of known immunoglobulin structures it has, nevertheless, been possible to predict successfully the conformation of hyper-variable loop regions of antibodies of known amino acid sequence. 

Within the last two years since the Sequencer of Beckman Instruments became generally available, the automated method has been successfully applied predominantly to comparisons of homologous proteins such as the immunoglobulins. Elucidation of the sequence of 20 to 30 N-terminal residues in peptides as long as the L-chains, comprising 214 amino acids or the H-chains with more than 400 residues would have been impossible to achieve by the manual procedure without prior cleavage of the molecules and isolation of the N-terminal regions. 

Brodeur, P.H. Riblet, R. (1984). The immunoglobulin heavy chain variable region (Igh-V) locus in the mouse. I. One hundred Igh-V genes comprise seven families of homologous genes. Eur. J. Immunol. 14,922-930. 

Hieter, P.A., Max, E.E., Seidman, J.G., Maizel, J.V., Jr., Leder, P. (1980). Cloned human and mouse kappa immunoglobulin constant and J region genes conserve homology in functional segments. Cell 22, 197-207. 

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