Serotransferrin 2-Transferrin

In the meantime, in 1947, Laurell and Ingelman[17] had independently purified the red protein from pig plasma and in the same year proposed the name transferrin which has since been adopted as the generic name of the proteins of this family serotransferrin (instead of siderophilin) present in blood and some external secretions, ovotransferrin (instead of conalbumin) in avian egg-white, lactotransferrin (also called lactoferrin) from milk, external secretions and leukocytes and melanotransferrin (instead of p97) in melanocyte and normal cell plasma membrane. A dozen mammalian and some frog, fish and insect serotransferrins were later isolated and characterized. 

Fig. 8. Primary structures of the glycans from rat serotransferrin (A,B,C)[221] and from rat mammary gland transferrin (D) [67]. R, GlcNAc(pl-4)[Fuc(al-6)]o- GlcNAc(P-N)Asn.

Fig. 16. Primary structure of glycans from turkey ovotransferrin (A) [119,238], hen ovotransferrin (B) [239, 240], chicken embryo serum (C), and chicken serotransferrin (D)[241]. R, GlcNAc(Pl-4)GlcNAc(Pl-N)Asn. Glycans of transferrin from embryo hepatocytes secreted into culture medium are a-l,6-fucosylated.

Human seminal transferrin. Human seminal transferrin (MM 80kDa) contains 6.1% sugars. The primary structure of the major N-linked glycan is identical to that of the serotransferrin diantennary glycan of Fig. 6A [247]. 

As mentioned above. X-ray diffraction of transferrin furnishes little information on the 3D-structure of the glycans and the images we have today remain largely speculative since they result from molecular modelling studies. We have represented in Fig. 21 the 3D-structure, determined by molecular modelling on the basis of X-ray diffraction data of rabbit serotransferrin [276] and of human lactotransferrin [89,92]. In rabbit serotransferrin, the single glycan linked to the peptide chain is immobilized into only... 

The transferrins are a group of specific metal-binding proteins, the best characterized of which are serotransferrin (present in blood plasma, milk, spinal fluid and semen), ovotransferrin (conalbumin present in avian and reptile egg white) and lactotransferrin (present in milk, pancreatic juice, tears and leucocytes). 

See Bezkorovainy (1980) for sources. Each transferrin can bind a maximum of 2 ferric iron atoms/protein molecule. Abbreviations SF, serotransferrin CA, conalbumin LF, lactoferrin. 

The iron-binding sites in lactoferrin are thought to lie deep within the protein structure, whereas in serotransferrin the iron lies closer to the surface (Krysteva et al, 1976). Resonance Raman spectra of diferric transferrins indicate that the phenolate groups of tyrisone are involved in the metal... 

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