Abstract
Antibody or γ globulin molecules synthesized within the cell or added to cell homogenates were found to be adsorbed and strongly bound to the ribosomes when these were subsequently extracted. Comparison of these proteins with others indicated that the extent of this binding could be affected by the pK of the protein. Measurements of the binding of γ globulin and light chains to ribosomes indicated that γ globulin has about 150 times as many binding sites/ribosome at saturation.
After a short pulse of 14C-amino acids, radioactive nascent peptides were removed from ribosomes by puromycin in a cell-free system. These peptides were largely of low moleculare wight, and adsorption on specific immunoadsorbents indicated the presence of heavy chain material but not of light chain determinants. These results suggest that assembly of rabbit IgG occurs between complete chains, and not by a combination of a complete light chain and a nascent heavy chain.
Footnotes
This investigation was supported by United States Public Health Service Research Grant HE-04598 from the National Heart Institute and United States Public Health Service Training Grant 5 T1 AI 154 from the National Institute of Allergy and Infectious Diseases.
