Protein isoform

Sakudoh, T., Tsuchida, K., and Kataoka, H. 2005. BmStartl, a novel carotenoid-binding protein isoform from Bombyx mori, is orthologous to MLN64, a mammalian cholesterol transporter. Biochem. Biophys. Res. Commun., 336(4) 1125—1135. 

These results are particularly relevant, since such constant interdistances may be related to the chemical properties of the proteins present in the sample. For example, they may be consistent with protein isoforms differing in a constant variation of the number of ionogenic groups in the molecule suggesting the presence of co- and post-translational modifications (Wilkins et al., 1997 Righetti et al., 2001 Mann and Jensen, 2003 Farriol-Mathis et al., 2004 Hamdan and Righetti, 2005). 

Konig J, Rost D, Cui Y, Keppler D. Characterization of the human multidrug resistance protein isoform MRP3 localized to the basolateral hepatocyte membrane. Hepatology 1999 29(4)7156-1163. 

Leinala, E. K., Davies, P. L., Doucet, D., Tyshenko, M. G., Walker, V. K., andjia, Z. (2002). A beta-helical antifreeze protein isoform with increased activity. Structural and functional insights./. Biol. Chem. 277, 33349-33352. 

Horiuchi, M., Baron, G. S., Xiong, L. W., and Caughey, B. (2001). Inhibition of interactions and interconversions of prion protein isoforms by peptide fragments from the C-terminal folded domain./. Biol. Chem. 276, 15489-15497. 

Isoenzymes arise when there exist different genes coding for the different proteins. Isoforms arise when the enzyme protein undergoes post translational modification, for example amino acid residue excision or addition of a non protein moiety such as sialic acid (a carbohydrate-like molecule). 

Sule, A., Vanrobaeys, R, Hajos, G., Van Beeumen, J., and Devreese, B., Proteomic analysis of small heat shock protein isoforms in barley shoots. Phytochemistry 65(12), 1853-1863, 2004. 

Efflux transporters, such as multidrug resistant protein, known as P-glycoprotein (Pgp), and related multidrug-resistant associated protein isoforms (MRPs), have been shown to be important for structurally diverse lipophilic compounds. Pgp and several MRPs, which were first identified in... 

MRPs Multidrug resistant-associated protein isoforms... 

Brietbart, R. E., A. Andreadis, and B. Nadal-Ginard, Alternative splicing A ubiquitous mechanism for the generation of multiple protein isoforms from single genes. Ann. Rev. Biochem. 56 467-495, 1987. 

In humans, SERCA pumps are encoded by three genes, ATP2A1-3, each encoding several protein isoforms (SERCAla,b, SERCA2a-c, SERCA3a-f, respectively) as a result of developmental or tissue-specific alternative splicing (Table 1). 

Liberatori, S., Canas, B., Tani, C., Bini, L., Buonocore, G., Godovac-Zimmermann, J., et al. (2004) Proteomic approach to the identification of VDACs protein isoforms in guinea pig brain synaptosomes. Proteomics 4, 1335-1360. 

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