EH domain

The EH domain is a member of the EF-hand family. The EF hand is a helix-loop-helix structural element in which the calcium ion is coordinated by a definitive arrangement of liganding residues. A pair of EF hands is observed to form a structurally stable unit (1). The EH domains form a distinct, specialized class within the EF-hand family. In contrast to other EF-hand proteins, which generally bind longer peptides with divergent sequences, EH domains bind to a short defined sequence of only 2 or 3 residues (2). Most EH domains bind asparagine-proline-phenylalanine (NPF). Almost all known binding partners include NPF sequences—for example, the Eps15 and POB1 proteins bind to Epsin (3,4), which has three NPF sequences. Eps15 also binds synaptojanin 1, which participates in synaptic vesicle endocytosis (5) and also has three NPF sequences. Structures of several EH domains without bound peptide have been solved from the Eps15 and Reps families (6-10) and structures are reported for one complex (11).

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In general, different NPF-containing proteins are found as binding partners for the different EH domain-containing proteins (2). A major question is how the selection is made. The human genome encodes 17 to 19 EH domains contained in 11 proteins that can be divided into 5 functional groups based on homology and domain structure: 1, Eps15 and the related protein Eps15R, which contain 3 EH domains each; 2, Intersectin, and its isoform intersectin-2, which contain 2 EH domains each; 3, Reps1 (and the related POB1/Reps2) containing 1 or 2 EH domains each; 4, gamma-synergin; and 5, the 4 EHD proteins, which contain 1 EH domain each. There are multiple (perhaps 30) potential binding proteins containing multiple NPF motifs.

EH domain containing proteins are generally involved in vesicle transport. They have been implicated in several signalling pathways, including signalling from the Ras-like protein, Ral (12). More recently, they have been shown to be important for the expression of glucose transporters in response to insulin (13).

1. Ikura, M. (1996) Calcium binding and conformational response in EF-hand proteins Trends in Biochem. Sci. 21, 14-17 2. Confalonieri, S., & Di Fiore, P. P. (2002) The Eps15 homology (EH) domain FEBS Lett 513, 24-29. 3. Chen, H., Fre, S., Slepnev, V. I., Capua, M. R., Takei, K., Butler, M. H., Di Fiore, P. P., & De Camilli, P. (1998) Epsin is an EH-domain-binding protein implicated in clathrin-mediated endocytosis Nature 394, 793-797. 4. Morinaka, K., Koyama, S., Nakashima, S., Hinoi, T., Okawa, K., Iwamatsu, A., & Kikuchi, A. (1999) Epsin binds to the EH domain of POB1 and regulates receptor-mediated endocytosis Oncogene 18, 5915-5922 5. McPherson, P. S., de Heuvel, E., Phillie, J., Wang, W., Sengar, A., & Egan, S. (1998) EH domain-dependent interactions between Eps15 and clathrin-coated vesicle protein p95 Biochem Biophys Res Commun 244, 701-705. 6. de Beer, T., Carter, R. E., Lobel-Rice, K. E., Sorkin, A., & Overduin, M. (1998) Structure and asn-pro-Phe binding pocket of the eps15 homology domain Science 281, 1357-1360 7. Koshiba, S., Kigawa, T., Iwahara, J., Kikuchi, A., & Yokoyama, S. (1999) Solution structure of the Eps15 homology domain of a human POB1 (partner of RalBP1) FEBS Lett 442, 138-142 8. Whitehead, B., Tessari, M., Carotenuto, A., van Bergen en Henegouwen, P. M., & Vuister, G. W. (1999) The EH1 domain of Eps15 is structurally classified as a member of the S100 subclass of EF-hand-containing proteins Biochemistry 38, 11271-11277 9. Enmon, J. L., de Beer, T., & Overduin, M. (2000) Solution Structure of Eps15's Third EH Domain Reveals Coincident Phe- Trp and Asn-Pro-Phe Binding Sites Biochemistry 39, 4309-4319 10. Kim, S., Cullis, D. N., Feig, L. A., & Baleja, J. D. (2001) Solution Structure of the Reps1 EH Domain and Characterization of Its Binding to NPF Target Sequences Biochemistry 40, 6776-6785 11. de Beer, T., Hoofnagle, A. N., Enmon, J. L., Bowers, R. C., Yamabhai, M., Kay, B. K., & Overduin, M. (2000) Molecular mechanism of NPF recognition by EH domains Nat Struct Biol 7, 1018-1022 12. Cullis, D. N., B. Philip, J. D. Baleja and L. A. Feig (2002). Rab11-FIP2, an Adaptor Protein Connecting Cellular Components Involved in Internalization and Recycling of Epidermal Growth Factor Receptors. J Biol Chem 277, 49158-66. 13. Guilherme, A., N. A. Soriano, P. S. Furcinitti and M. P. Czech (2004). Role of EHD1 and EHBP1 in Perinuclear Sorting and Insulin-regulated GLUT4 Recycling in 3T3-L1 Adipocytes. J Biol Chem 279, 40062-75.