Pancreas into microsomes

Sulfuric acid, phosphate, and sucrose extracts of mouse and beef pancreas have also been compared chromatographically on Amberlite IRC-50 (154). For both species, the sulfuric acid extracts give two peaks which correspond to ribonucleases A and B. When prepared from supernatant free of zymogen granules and microsomes, phosphate and sucrose preparations give a third peak, (10-15 % of the total activity in the case of mouse 1 % in the case of beef) which can be converted into the previous ones by acid treatment. This treatment induces a two- to three-fold increase in activity and the dissociation of the acidic compound already referred to above. The chemical structure of mouse ribonuclease(s) is still unknown. 

GGT is present (in decreasing order of abundance) in proximal renal tubule, liver, pancreas, and intestine. The enzyme is present in cytoplasm (microsomes), but the larger fraction is located in the cell membrane and may transport amino acids and peptides into the cell across the cell membrane in the form of y-glutamyl peptides. It may also be involved in some aspects of glutathione metabolism. ... 

Despite earlier suspicions, it is now well established that mitochondria from a variety of sources can incorporate amino acids into protein independently of the microsomal fraction. But, with the exception of muscle tissue (67), the initial rate (1-5 min after injection of the isotope) of amino acid incorporation into mitochondria of animal tissues, in vivo, is much less than that of the microsomal fraction. The ratio of the specific activities of these two fractions, however, varies considerably from tissue to tissue (276)-, for rat liver, for example, it is 5, whereas for guinea pig pancreas it is only 1.8. After longer periods, since the specific activity of the microsomal fraction reaches a saturation value after about 10 min, the specific as well as the total activity of the mitochondria eventually surpasses that of the microsomes in most tissues. In plants, mitochondria seem to be relatively more active than in animals (68, 69). 

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