Open AccessProteolytic activity in erythrocyte precursors
Author(s) -
Samir Hanash,
Donald L. Rucknagel
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.7.3427
Subject(s) - globin , thalassemia , proteolysis , beta (programming language) , bone marrow , tetramer , hemoglobin , alpha (finance) , beta thalassemia , biology , biochemistry , chemistry , microbiology and biotechnology , immunology , genetics , enzyme , medicine , construct validity , nursing , patient satisfaction , computer science , programming language
Thalassemia is characterized by unequal rates of synthesis of the α and β globin chains that are part of the hemoglobin tetramer. In the type of thalassemia due to a defect in β-chain synthesis (β-thalassemia), this imbalance results in a relative exoess of α-chains. We have studied the susceptibility of excess free α-chains to proteolysis. Incubation of isotopically labeled peripheral blood lysates from individuals with β-thalassemia trait in the presence of bone marrow or normoblast lysates from thalassemic or hematologically normal individuals resulted in a decrease in the α/β ratio and a loss of free α-chain radioactivity. Neither contamination with leukocytes nor higher ATP contents in young erythrocytes appeared to be responsible for this activity in normoblasts and bone marrow. We propose that erythroid precursor cells possess proteolytic activity that is markedly diminished in mature cells. This activity serves an important control function in the regulation of hemoglobin synthesis. It accounts at least in part for the more balanced synthesis of α- and β-chains observed in bone marrow than in peripheral blood in heterozygous β-thalassemia. It also plays a fine-tuning role in maintaining balanced synthesis in non-thalassemic erythrocytes.