Hemoglobin embryonic

A third embryonic hemoglobin, termed Hb-Portland 1, has recently been described (Cl, C2, H6, T8, W17). The protein was first discovered in a malformed newborn with a complex autosomal chromosomal mosaicism. However, it is probably also present for some 0.5 to 5% in newborn infants with a D, trisomy and in very small amounts (0.1-0.2%) in normal newborns. Hb-Portland 1 does not contain a chains but is composed of one pair of y chains and one pair of chains which have been termed C chains. The C chain is probably a normal embryonic hemoglobin chain. Hb-Portland 1 does react with free a chains to form Hb-F or aayz and a aafa component (T8). It seems, therefore, that the chain can combine with the a chain, but the afiSnity of the a chain for the C chain is apparently lower than for either the e chain or y chain. Embryonic hemoglobins have also been found in several mammalian species, such as the pig, cattle, and sheep (K13, K15). 

During development, the synthesis of embryonic hemoglobin polypeptide chain (s) is succeeded by that of the y chains and at a later stage by that of the p and 8 (Fig. 9). The ontogeny of these hemoglobin chains is thoroughly reviewed by Kleihauer (K15), and Fig. 9 is based on information taken from that reference. Hb-Gower-1, or u, is the major... 

H30. Huehns, E. R., Dance, N., Beaven, G. H., Hecht, F., and Motulsky, A. G., Human embryonic hemoglobins. Cold Spring Harbor Symp. Quant. Biol. 29, 327-331 (1964). 

K17. Kleihauer, E. F., Tang, T. E., and Betke, K., The intracellular distribution of embryonic hemoglobin in red blood cells of human embryos. A contribution to the ontogenesis of human hemoglobin. Acta Haematol. 38, 264-272 (1967). 

Human embryonic hemoglobins. Cold Spring Harbor Symp Quant Biol 1965 29 327-331.)... 

Fetal blood is produced first by the embryonic yolk sac, then by the liver, and finally by the fetal bone marrow. The yolk sac produces three embryonic hemoglobins Portland ( 2 2)> Gower-1 2 1) > and Gower-2 (aze2). These normal embryonic hemoglobins are of little importance in clinical chemistry because they are present in fetal blood only in the first trimester. 

M4. Malik, Z., and Djaldetti, M., Glycosylation of mouse embryonic hemoglobins in cultured yolk sac erythroblasts. Biol. Neonate 35, 221-223 (1979). 

Wilt, F.H. Heme and regulation of embryonic hemoglobin synthesis. 68. Biochem. biophys. Res. Commun. 33, 113-118 (1968)... 

Erythrocytes containing embryonic hemoglobin are replaced byerythro-cytes containing fetal hemoglobin (ttiY j. 

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