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PMID:22532867

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Citation

Greibe, E, Fedosov, S and Nexo, E (2012) The cobalamin-binding protein in zebrafish is an intermediate between the three cobalamin-binding proteins in human. PLoS ONE 7:e35660

Abstract

In humans, three soluble extracellular cobalamin-binding proteins; transcobalamin (TC), intrinsic factor (IF), and haptocorrin (HC), are involved in the uptake and transport of cobalamin. In this study, we investigate a cobalamin-binding protein from zebrafish (Danio rerio) and summarize current knowledge concerning the phylogenetic evolution of kindred proteins. We identified a cobalamin binding capacity in zebrafish protein extracts (8.2 pmol/fish) and ambient water (13.5 pmol/fish) associated with a single protein. The protein showed resistance toward degradation by trypsin and chymotrypsin (like human IF, but unlike human HC and TC). The cobalamin analogue, cobinamide, bound weaker to the zebrafish cobalamin binder than to human HC, but stronger than to human TC and IF. Affinity for another analogue, adenosyl-pseudo-cobalamin was low compared with human HC and TC, but high compared with human IF. The absorbance spectrum of the purified protein in complex with hydroxo-cobalamin resembled those of human HC and IF, but not TC. We searched available databases to further explore the phylogenies of the three cobalamin-binding proteins in higher vertebrates. Apparently, TC-like proteins are the oldest evolutionary derivatives followed by IF and HC (the latter being present only in reptiles and most but not all mammals). Our findings suggest that the only cobalamin-binding protein in zebrafish is an intermediate between the three human cobalamin binders. These findings support the hypothesis about a common ancestral gene for all cobalamin-binding proteins in higher vertebrates.

Links

PubMed PMC3331988 Online version:10.1371/journal.pone.0035660

Keywords

Animals; Biological Transport; Protein Binding; Transcobalamins/chemistry; Transcobalamins/metabolism; Vitamin B 12/metabolism; Zebrafish/metabolism; Zebrafish Proteins/chemistry; Zebrafish Proteins/metabolism

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

DANRE:F1QJR9

enables

GO:0031419: cobalamin binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

DANRE:F2Z4S3

enables

GO:0031419: cobalamin binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

DANRE:F2Z4S7

enables

GO:0031419: cobalamin binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

DANRE:Q6PG35

enables

GO:0031419: cobalamin binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete


See also

References

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