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Gene Review

TCN2  -  transcobalamin II

Homo sapiens

Synonyms: D22S676, D22S750, II, TC, TC II, ...
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Disease relevance of TCN2

  • Effect of TCN2 776C>G on vitamin B12 cellular availability in end-stage renal disease patients [1].
  • The MTHFD1 R653Q, SLC19A1 R27H, and TCN2 P259R polymorphisms showed no significant association with omphalocele [2].
  • In genetic disorders that are characterized by congenital deficiency of TCII, intracellular Cbl deficiency occurs, resulting in an early onset of megaloblastic anemia that is sometimes accompanied by a neurologic disorder [3].
  • Functional human transcobalamin II isoproteins are secreted by insect cells using the baculovirus expression system [4].
  • One consensus and two atypical motifs for the c-myc ligand are located downstream and upstream, respectively, of the GC box, and this could explain the elevated plasma TCII observed in some patients with multiple myeloma, as the c-myc product is overexpressed in some myeloma cells [3].

Psychiatry related information on TCN2


High impact information on TCN2


Chemical compound and disease context of TCN2


Biological context of TCN2


Anatomical context of TCN2

  • TCII did not accumulate in the SF9 cells and seemed to be constitutively secreted as observed previously in cultured human endothelial cells [4].
  • The recombinant TCII cross-reacts with an antiserum to native human TCII, binds Cbl and facilitates the uptake of Cbl in eukaryotic cells by binding to the receptor for TCII-Cbl on the plasma membrane of K562 cells [4].
  • RESULTS: Holo-transcobalamin II levels were normal or supranormal in all patients and showed a linear association with albumin (r = 0.205, P = 0.025) and with vitamin B12 (r = 0.778, P = 0.001), but not with age, creatinine, body mass index, tHcy, ln-tHcy, vitamin B6, plasma folate, and red blood cell folate concentration [1].
  • The enhancer activity of the oligomerized SV40 TC-I and TC-II sequences has been investigated in lymphoid and non-lymphoid cell lines [12].
  • This TC-II enhanson, which is identical to the kappa B motif from the kappa chain enhancer, was active in both lymphoid and non-lymphoid cells, which contrasts with the previously reported lymphoid cell specificity of the kappa B motif [12].

Associations of TCN2 with chemical compounds

  • CONCLUSION: We conclude from this largest study on the subject thus far that there are no associations between allelic variants of TCN2 776C>G and plasma vitamin B(12), folate, or total homocysteine plasma levels in kidney transplant patients [17].
  • Effects of TCN2 776C>G on vitamin B, folate, and total homocysteine levels in kidney transplant patients [17].
  • For all study participants, total TC was associated with holoTC and number of TCN2 766C alleles; in female participants only, total TC was also associated with age, homocysteine, and cysteine [19].
  • However, in contrast to the TC-II enhanson, the H-2Kb enhanson exhibits a very low activity in HeLa cells, but can be strongly induced by TPA and/or cycloheximide treatments which suggests that its cognate factor is inactivated (repressed) by an inhibitor protein [12].
  • Furthermore, complex formation between the TC-IIA protein and the TC-II enhanson was efficiently competed by the kappa B motif from the kappa chain enhancer, indicating that TC-IIA is the NF-kappa B factor or a closely related protein [20].

Physical interactions of TCN2


Other interactions of TCN2

  • A number of the exon/intron splice junctions of human TCII, TCI, and IF genes are located in homologous regions of these proteins, providing evidence that these genes have evolved by duplication of an ancestral gene [3].
  • The TC2 group, which showed extra copies of the CCND1 locus and no IGH translocations or the chromosome 13q deletion, was characterized by the overexpression of genes involved in protein biosynthesis at the translational level [23].
  • Stimulation with anti-CD3/CD28 antibodies increased the percentage of TC2 cells and decreased the percentage of TH2 cells [24].
  • Increased TCII levels found in ACD may be explained by the higher degree of RA activity in these patients, and could also be viewed as a compensatory reaction to anaemia or reduced vitamin B12 levels [25].
  • These results suggest that megalin contains a distinct single high-affinity binding site for TC II-R and their association in the native renal BBM is important for tubular reabsorption of many proteins, including TC II [21].

Analytical, diagnostic and therapeutic context of TCN2


  1. Effect of TCN2 776C>G on vitamin B12 cellular availability in end-stage renal disease patients. Födinger, M., Veitl, M., Skoupy, S., Wojcik, J., Röhrer, C., Hagen, W., Puttinger, H., Hauser, A.C., Vychytil, A., Sunder-Plassmann, G. Kidney Int. (2003) [Pubmed]
  2. Folate-related genes and omphalocele. Mills, J.L., Druschel, C.M., Pangilinan, F., Pass, K., Cox, C., Seltzer, R.R., Conley, M.R., Brody, L.C. Am. J. Med. Genet. A (2005) [Pubmed]
  3. The cloning and characterization of the human transcobalamin II gene. Regec, A., Quadros, E.V., Platica, O., Rothenberg, S.P. Blood (1995) [Pubmed]
  4. Functional human transcobalamin II isoproteins are secreted by insect cells using the baculovirus expression system. Quadros, E.V., Sai, P., Rothenberg, S.P. Blood (1993) [Pubmed]
  5. A new case of deficiency of the R binder for cobalamin, with observations on minor cobalamin-binding proteins in serum and saliva. Carmel, R. Blood (1982) [Pubmed]
  6. Modified therapeutic community for homeless mentally ill chemical abusers: treatment outcomes. De Leon, G., Sacks, S., Staines, G., McKendrick, K. The American journal of drug and alcohol abuse. (2000) [Pubmed]
  7. Assessment of the general health profile trends in the male population of Tallinn, Estonia. Volozh, O., Deev, A., Solodkaya, E., Abina, J., Kalyuste, T., Kaup, R., Goldsteine, G., Olferiev, A. Public health. (1998) [Pubmed]
  8. Hereditary abnormal transcobalamin II previously diagnosed as congenital dihydrofolate reductase deficiency. Hoffbrand, A.V., Tripp, E., Jackson, B.F., Luck, W.E., Frater-Schröder, M. N. Engl. J. Med. (1984) [Pubmed]
  9. Studies of a patient with megaloblastic anemia and an abnormal transcobalamin II. Seligman, P.A., Steiner, L.L., Allen, R.H. N. Engl. J. Med. (1980) [Pubmed]
  10. Changes in circulating transcobalamin II after injection of cyanocobalamin. Donaldson, R.M., Brand, M., Serfilippi, D. N. Engl. J. Med. (1977) [Pubmed]
  11. Increased circulating levels of transcobalamin ii in gaucher's disease. Gilbert, H.S., Weinreb, N. N. Engl. J. Med. (1976) [Pubmed]
  12. The SV40 TC-II(kappa B) and the related H-2Kb enhansons exhibit different cell type specific and inducible proto-enhancer activities, but the SV40 core sequence and the AP-2 binding site have no enhanson properties. Kanno, M., Fromental, C., Staub, A., Ruffenach, F., Davidson, I., Chambon, P. EMBO J. (1989) [Pubmed]
  13. Nonsynonymous polymorphisms in genes in the one-carbon metabolism pathway and associations with colorectal cancer. Koushik, A., Kraft, P., Fuchs, C.S., Hankinson, S.E., Willett, W.C., Giovannucci, E.L., Hunter, D.J. Cancer Epidemiol. Biomarkers Prev. (2006) [Pubmed]
  14. Receptors for transferrin and transcobalamin II display segregated distribution on microvilli of leukemia L1210 cells. Kishimoto, T., Tavassoli, M., Green, R., Jacobsen, D.W. Biochem. Biophys. Res. Commun. (1987) [Pubmed]
  15. Hereditary partial transcobalamin II deficiency with neurologic, mental and hematologic abnormalities in children and adults. Teplitsky, V., Huminer, D., Zoldan, J., Pitlik, S., Shohat, M., Mittelman, M. Isr. Med. Assoc. J. (2003) [Pubmed]
  16. Serum transcobalamin II levels in patients with malaria infection. Areekul, S., Churdchu, K., Cheeramakara, C., Wilairatana, P., Charoenlarp, P. Southeast Asian J. Trop. Med. Public Health (1995) [Pubmed]
  17. Effects of TCN2 776C>G on vitamin B, folate, and total homocysteine levels in kidney transplant patients. Winkelmayer, W.C., Skoupy, S., Eberle, C., Födinger, M., Sunder-Plassmann, G. Kidney Int. (2004) [Pubmed]
  18. Linkage studies of cholestasis familiaris groenlandica/Byler-like disease with polymorphic protein and blood group markers. Eiberg, H., Nielsen, I.M. Hum. Hered. (1993) [Pubmed]
  19. Holotranscobalamin and total transcobalamin in human plasma: determination, determinants, and reference values in healthy adults. Refsum, H., Johnston, C., Guttormsen, A.B., Nexo, E. Clin. Chem. (2006) [Pubmed]
  20. The SV40 TC-II(kappa B) enhanson binds ubiquitous and cell type specifically inducible nuclear proteins from lymphoid and non-lymphoid cell lines. Macchi, M., Bornert, J.M., Davidson, I., Kanno, M., Rosales, R., Vigneron, M., Xiao, J.H., Fromental, C., Chambon, P. EMBO J. (1989) [Pubmed]
  21. Transcobalamin II receptor interacts with megalin in the renal apical brush border membrane. Yammani, R.R., Seetharam, S., Dahms, N.M., Seetharam, B. J. Membr. Biol. (2003) [Pubmed]
  22. Cellular import of cobalamin (Vitamin B-12). Seetharam, B., Bose, S., Li, N. J. Nutr. (1999) [Pubmed]
  23. Molecular classification of multiple myeloma: a distinct transcriptional profile characterizes patients expressing CCND1 and negative for 14q32 translocations. Agnelli, L., Bicciato, S., Mattioli, M., Fabris, S., Intini, D., Verdelli, D., Baldini, L., Morabito, F., Callea, V., Lombardi, L., Neri, A. J. Clin. Oncol. (2005) [Pubmed]
  24. Cytokine production by bronchoalveolar lavage T lymphocytes in chronic obstructive pulmonary disease. Barczyk, A., Pierzchała, W., Kon, O.M., Cosio, B., Adcock, I.M., Barnes, P.J. J. Allergy Clin. Immunol. (2006) [Pubmed]
  25. Elevated serum transcobalamin levels in anaemia of rheumatoid arthritis: correlation with disease activity but not with serum tumour necrosis factor alpha and interleukin 6. Vreugdenhil, G., Lindemans, J., van Eijk, H.G., Swaak, A.J. J. Intern. Med. (1992) [Pubmed]
  26. Measurement of vitamin B12-binding proteins of plasma. I. Technique. Begley, J.A., Hall, C.A. Blood (1975) [Pubmed]
  27. Identification of two mutant alleles of transcobalamin II in an affected family. Li, N., Rosenblatt, D.S., Kamen, B.A., Seetharam, S., Seetharam, B. Hum. Mol. Genet. (1994) [Pubmed]
  28. Purification and molecular characterization of human transcobalamin II. Quadros, E.V., Rothenberg, S.P., Pan, Y.C., Stein, S. J. Biol. Chem. (1986) [Pubmed]
  29. Monoclonal antibodies against Trypanosoma cruzi neuraminidase reveal enzyme polymorphism, recognize a subset of trypomastigotes, and enhance infection in vitro. Prioli, R.P., Mejia, J.S., Pereira, M.E. J. Immunol. (1990) [Pubmed]
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