QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hubbard, C. Articles by Castle, D. Search for Related Content PubMed PubMed Citation Articles by Hubbard, C. Articles by Castle, D.

Vol. 11, Issue 9, 2933-2947, September 2000

The Secretory Carrier Membrane Protein Family: Structure and Membrane Topology

Charles Hubbard,^* David Singleton,^* Michelle Rauch, Sajith Jayasinghe,^§ David Cafiso, and David Castle^*

 ^*Department of Cell Biology, University of Virginia Health Sciences Center; and  Department of Chemistry, University of Virginia, Charlottesville, Virginia 22908

Secretory carrier membrane proteins (SCAMPs) are integral membrane proteins found in secretory and endocytic carriers implicated to function in membrane trafficking. Using expressed sequence tag database and library screens and DNA sequencing, we have characterized several new SCAMPs spanning the plant and animal kingdoms and have defined a broadly conserved protein family. No obvious fungal homologue has been identified, however. We have found that SCAMPs share several structural motifs. These include NPF repeats, a leucine heptad repeat enriched in charged residues, and a proline-rich SH3-like and/or WW domain-binding site in the N-terminal domain, which is followed by a membrane core containing four putative transmembrane spans and three amphiphilic segments that are the most highly conserved structural elements. All SCAMPs are 32-38 kDa except mammalian SCAMP4, which is ~25 kDa and lacks most of the N-terminal hydrophilic domain of other SCAMPs. SCAMP4 is authentic as determined by Northern and Western blotting, suggesting that this portion of the larger SCAMPs encodes the functional domain. Focusing on SCAMP1, we have characterized its structure further by limited proteolysis and Western blotting with the use of isolated secretory granules as a uniformly oriented source of antigen and by topology mapping through expression of alkaline phosphatase gene fusions in Escherichia coli. Results show that SCAMP1 is degraded sequentially from the N terminus and then the C terminus, yielding an ~20-kDa membrane core that contains four transmembrane spans. Using synthetic peptides corresponding to the three conserved amphiphilic segments of the membrane core, we have demonstrated their binding to phospholipid membranes and shown by circular dichroism spectroscopy that the central amphiphilic segment linking transmembrane spans 2 and 3 is -helical. In the intact protein, these segments are likely to reside in the cytoplasm-facing membrane interface. The current model of SCAMP1 suggests that the N and C termini form the cytoplasmic surface of the protein overlying a membrane core, which contains a functional domain located at the cytoplasmic interface with little exposure of the protein on the ectodomain.

---

Present addresses: Department of Pathology, University of Virginia Health Sciences Center, Charlottesville, VA 22908; ^§Department of Biophysics, University of California at Irvine, Irvine, CA 92717.

Corresponding author. E-mail address: jdc4r{at}virginia.edu.

---

Molecular Biology of the Cell
Vol. 11, 2933-2947, September 2000
Copyright © 2000 by The American Society for Cell Biology

This article has been cited by other articles:

				G. H. Diering, J. Church, and M. Numata Secretory Carrier Membrane Protein 2 Regulates Cell-surface Targeting of Brain-enriched Na+/H+ Exchanger NHE5 J. Biol. Chem., May 15, 2009; 284(20): 13892 - 13903. [Abstract] [Full Text] [PDF]

				Q. L. Aoh, A. M. Castle, C. H. Hubbard, O. Katsumata, and J. D. Castle SCAMP3 Negatively Regulates Epidermal Growth Factor Receptor Degradation and Promotes Receptor Recycling Mol. Biol. Cell, March 15, 2009; 20(6): 1816 - 1832. [Abstract] [Full Text] [PDF]

				C. Han, T. Chen, M. Yang, N. Li, H. Liu, and X. Cao Human SCAMP5, a Novel Secretory Carrier Membrane Protein, Facilitates Calcium-Triggered Cytokine Secretion by Interaction with SNARE Machinery J. Immunol., March 1, 2009; 182(5): 2986 - 2996. [Abstract] [Full Text] [PDF]

				H. Zhao, X. Zheng, X. Yuan, L. Wang, X. Wang, Y. Zhong, Z. Xie, and T. Tully ben Functions with Scamp during Synaptic Transmission and Long-Term Memory Formation in Drosophila J. Neurosci., January 14, 2009; 29(2): 414 - 424. [Abstract] [Full Text] [PDF]

				X. Chen, P. J. Ulintz, E. S. Simon, J. A. Williams, and P. C. Andrews Global Topology Analysis of Pancreatic Zymogen Granule Membrane Proteins Mol. Cell. Proteomics, December 1, 2008; 7(12): 2323 - 2336. [Abstract] [Full Text] [PDF]

				M. Gonzalez-Aguero, L. Pavez, F. Ibanez, I. Pacheco, R. Campos-Vargas, L. A. Meisel, A. Orellana, J. Retamales, H. Silva, M. Gonzalez, et al. Identification of woolliness response genes in peach fruit after post-harvest treatments J. Exp. Bot., May 3, 2008; (2008) ern069v1. [Abstract] [Full Text] [PDF]

				H. Liao, J. Zhang, S. Shestopal, G. Szabo, A. Castle, and D. Castle Nonredundant function of secretory carrier membrane protein isoforms in dense core vesicle exocytosis Am J Physiol Cell Physiol, March 1, 2008; 294(3): C797 - C809. [Abstract] [Full Text] [PDF]

				H. K. Muller, O. Wiborg, and J. Haase Subcellular Redistribution of the Serotonin Transporter by Secretory Carrier Membrane Protein 2 J. Biol. Chem., September 29, 2006; 281(39): 28901 - 28909. [Abstract] [Full Text] [PDF]

				L. Liu, H. Liao, A. Castle, J. Zhang, J. Casanova, G. Szabo, and D. Castle SCAMP2 Interacts with Arf6 and Phospholipase D1 and Links Their Function to Exocytotic Fusion Pore Formation in PC12 Cells Mol. Biol. Cell, October 1, 2005; 16(10): 4463 - 4472. [Abstract] [Full Text] [PDF]

				A. Castle and D. Castle Ubiquitously expressed secretory carrier membrane proteins (SCAMPs) 1-4 mark different pathways and exhibit limited constitutive trafficking to and from the cell surface J. Cell Sci., August 15, 2005; 118(16): 3769 - 3780. [Abstract] [Full Text] [PDF]

				P. J. C. Lin, W. P. Williams, Y. Luu, R. S. Molday, J. Orlowski, and M. Numata Secretory carrier membrane proteins interact and regulate trafficking of the organellar (Na+,K+)/H+ exchanger NHE7 J. Cell Sci., May 1, 2005; 118(9): 1885 - 1897. [Abstract] [Full Text] [PDF]

				F. Baluska, J. Samaj, P. Wojtaszek, D. Volkmann, and D. Menzel Cytoskeleton-Plasma Membrane-Cell Wall Continuum in Plants. Emerging Links Revisited Plant Physiology, October 1, 2003; 133(2): 482 - 491. [Full Text] [PDF]

				L. Liu, Z. Guo, Q. Tieu, A. Castle, and D. Castle Role of Secretory Carrier Membrane Protein SCAMP2 in Granule Exocytosis Mol. Biol. Cell, December 1, 2002; 13(12): 4266 - 4278. [Abstract] [Full Text] [PDF]

				Z. Guo, L. Liu, D. Cafiso, and D. Castle Perturbation of a Very Late Step of Regulated Exocytosis by a Secretory Carrier Membrane Protein (SCAMP2)-derived Peptide J. Biol. Chem., September 13, 2002; 277(38): 35357 - 35363. [Abstract] [Full Text] [PDF]