Amino-Acid Sequence of the Variable Region of the Heavy (Alpha) Chain of a Mouse Myeloma Protein with Anti-Hapten Activity

Amino-Acid Sequence of the Variable Region of the Heavy (Alpha) Chain of a Mouse Myeloma Protein with Anti-Hapten Activity

Department of Microbiology, Washington University School of Medicine, St. Louis, Missouri
^‡Division of Biology, California Institute of Technology, Pasadena, Calif.

Abstract

Cyanogen bromide cleavage of the heavy (alpha) chain of protein 315 (an immunoglobulin A mouse myeloma protein with anti-dinitrophenyl activity) yielded five fragments of which one (CN2), with 156 residues, contained the chain's entire variable region. Determination of the amino-acid sequence of CN2 showed that: (1) the variable region has appreciable homology (about 33% identities) with the variable region of the light chain from the same molecule; and (2) the constant-region sequence immediately following the probable transition from variable to constant domains is the same in the protein-315 α as in human γ1 and μ chains (-Val-Ser-Ser-). The sequence of the cyanogen bromide octapeptide (CN5) from the carboxy terminus of the protein-315 heavy chain closely resembles the corresponding segments of human α and μ chains.

Footnotes

↵ * Present address: National Heart and Lung Institute, National Institutes of Health, Bethesda, Md.
↵ † Present address: Department of Chemical Pathology, Guys Hospital Medical School, London, England.
↵ § To whom requests for reprints should be sent. Present address: Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Mass. 02139.