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Minor early embryonic chick hemoglobin M. Amino acid sequences of the epsilon and alpha D chains
Insights
Early chick embryos have four hemoglobins. This study details the amino acid sequences of HbM, revealing its beta-like chain is identical to HbE
Area of Science:
- Biochemistry
- Developmental Biology
- Genetics
Background:
- Early chick embryos (Gallus gallus domesticus) express multiple hemoglobin types.
- Four distinct hemoglobins, two major and two minor, are present in embryonic erythrocytes.
- Hemoglobin M (HbM) is the least abundant of these embryonic hemoglobins.
Observation:
- Amino acid sequences for the beta-like and alpha-like chains of HbM were determined.
- The beta-like chain of HbM shares an identical amino acid sequence with the epsilon chain of HbE.
- The alpha-like chain of HbM exhibits significant sequence similarity to the adult alpha D chain.
Findings:
- The complete amino acid sequence of the beta-like chain of HbM is identical to the epsilon chain of HbE.
- Analysis of the alpha-like chain of HbM (92 of 141 residues) shows close relation to the minor adult alpha D chain.
- Sequence data and nucleotide analysis suggest a single gene encodes both embryonic and adult alpha D globin polypeptides.
Implications:
- Provides insights into the structural and functional diversity of embryonic hemoglobins.
- Suggests a potential gene duplication or regulatory mechanism for alpha-globin evolution in chickens.
- Contributes to understanding hemoglobin switching during avian development.
Abstract:
Erythrocytes of the early chick embryo contain four hemoglobins, two major and two minor. In this paper, we present amino acid sequences for the beta-like and alpha-like chains of HbM, the least abundant of the four early chick hemoglobins. The complete amino acid sequence of the beta-like chain of HbM is identical with that of the epsilon chain of HbE, the other minor early embryonic hemoglobin in the domestic chicken. Analysis of the alpha-like chain of HbM (92 of 141 residues) reveals a globin sequence closely related to the minor adult alpha D chain. Comparison of our sequence data with the nucleotide sequence of the alpha D globin gene suggests that a single gene encodes both the embryonic and adult alpha D globin polypeptides. We discuss the structure, possible function, and evolution of the HbM globin chains.