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Cotranslational heme binding to nascent globin chains
A A Komar1, A Kommer, I A Krasheninnikov
1Department of Molecular Biology, Faculty of Biology, Moscow State University, Russian Federation.
FEBS Letters
|July 12, 1993
Summary
This study shows that heme binds to the globin protein while it is still being synthesized on the ribosome. This suggests a cotranslational process for globin folding and heme incorporation.
Area of Science:
- Molecular Biology
- Protein Synthesis
- Biochemistry
Background:
- Globin synthesis is a fundamental process in red blood cell development.
- Heme is a critical component of hemoglobin, essential for oxygen transport.
Purpose of the Study:
- To investigate the timing of heme binding during globin synthesis.
- To explore the relationship between globin folding and heme incorporation.
Main Methods:
- Cell-free synthesis of globin using rabbit reticulocyte extracts.
- Incorporation of 3H-labeled hemin during synthesis.
- Analysis of radiolabeled components using sucrose gradient centrifugation and puromycin treatment.
Main Results:
- 3H-labeled hemin was found associated with polyribosomes during globin synthesis.
- Puromycin treatment released both 3H-hemin and 14C-leucine labeled polypeptide from polyribosomes.
- This indicates that hemin is bound to nascent globin chains.
Conclusions:
- Globin folding and heme binding occur concurrently with protein synthesis (cotranslationally).
- The ribosome serves as a platform for both globin chain elongation and heme acquisition.
- This cotranslational mechanism is crucial for the proper assembly of functional hemoglobin.