The Complete Amino Acid Sequence of Rat β2‐Microglobulin

The primary structure of rat beta 2-microglobulin (beta 2m) was determined. It is a polypeptide of 99 amino acids with the following sequence: IQKTPQIQVY SRHPPENGKP NFLNCYVSQF HPPQIEIELL KNGKKIPNIE MSDLSFSKDW SFYILAHTEF TPTETDVYAC RVKHVTLKEP KTVTWDRDM. The primary structure was determined by NH2-terminal sequence analysis together with sequence determination of one cyanogen bromide fragment and one tryptic peptide. Of other known beta 2m sequences, rat beta 2m is most homologous to mouse beta 2m (83% identity). The rabbit, human, and guinea pig sequences are more distant, with 24, 27, and 31% differences, respectively.