CATABOLISM OF RAT BETA-2-MICROGLOBULIN IN RAT

Abstract

Highly purified rat .beta.2-microglobulin (.beta.2m), cytochrome c and lysozyme were radiolabeled and their catabolism studied in the rat. More than 90% of these low MW proteins were removed from the serum within 1 h and excreted into the urine by 24 h. Except for the kidney in which the concentration of these proteins was 10- to 20-fold greater than in the serum, there was little evidence that rat tissues were concentrating these proteins. The stomach concentrated radioiodine. The catabolism of rat .beta.2m differed from that of cytochrome c and lysozyme in that the kidney contained twice as much labeled rat .beta.2m. The rat excreted 10-15% of the injected rat .beta.2m but only 1-5% of the cytochrome c or lysozyme. These studies established a basis for turnover studies of .beta.2m complexed with other cell membrane proteins, e.g., HL-A or H-2 peptides.