N-terminal transmembrane domains

Synaptotagmins comprise a small family of single-membrane spanning proteins that are expressed in neurons and neuroendocrine cells. So far 16 members have been identified in vertebrates (Craxton 2004). They contain an N-terminal transmembrane domain followed by a variable linker region and two C2 domains which are connected by a short linker (Stidhof 2002). Some synaptotagmins have additional short... 

Bakos E, Evers R, Szakacs G, Gabor ET, Welker E, Szabo K, de Haas M, van Lies-beth D, Borst P, Varadi A, Sarkadi B (1998) Functional multidrug resistance protein (MRP1) lacking the N-terminal transmembrane domain. J Biol Chem 273 32167-32175... 

Wang W, Chan JY (2006) Nrfl is targeted to the endoplasmic reticulum membrane by an N-terminal transmembrane domain. Inhibition of nuclear translocation and transacting function. J Biol Chem 281 19676-19687... 

Vpu, viral protein U, an integral membrane 81-peptide (Mr 16 kDa) encoded by the HIV-1 genome and playing an important role in the viral life cyde. Vpu both enhances virion rdease from human cells and the degradation of CD4, the cellular surface receptor of HIV-1. The oligomeric N-terminal transmembrane domain forms a cation-specific ion channel which is responsible for the enhanced release of mature vims particles from the cell surface. In... 

Most types of collagen are extracellular matrix proteins but four of the vertebrate collagens (XIII, XVII, XXIII, and XXV) are classified as type II membrane proteins. They contain an N-terminal cytoplasmic domain, a transmembrane domain, and an extracellular collagenous domain. Also, a membrane-bound protein, ectodys-plasin-A, is a membrane protein with 19 -Gly-Xaa-Yaa- repeat. Macrophage scavenger receptor, ... 

The definition of the primary structure of synaptotagmin-1, composed of an N-terminal transmembrane region and two C-terminal C2-domains (Figure 3), led... 

Synaptobrevin 2 is a small protein composed of 118 amino acids. It contains a SNARE motif with a short N-terminal proline-rich extension but lacks an independently folded N-terminal domain. Like syntaxin 1, the protein possesses a C-terminal transmembrane domain that is connected to the SNARE motif by a short linker (Figure 1). Synaptobrevin is palmitoylated at cysteine residues close to its transmembrane domain. Synaptobrevin 2 is highly expressed in neurons and neuroendocrine cells, but unlike syntaxin 1 it is also present in many non-neuronal tissues albeit at low levels. 

The structures of three cytokine receptor C2HRs and tissue factor (TF) have been determined (see Table I and Chill et al., 2003 Harlos et at, 1994 Josephson et al, 2001 Randal and Kossiakoff, 2001 Thiel et al., 2000 Walter et al, 1995). The general features of the C2HR are shown in Fig. 8. It consists of two /3-sandwich domains, D1 and D2, connected by a short linker containing 1 turn of a- or 3io helix. The cytokine binding site is comprised predominantly of the loops located at the D1 and D2 interface. The N-terminal D1 domain is most distal from the cell membrane, while the G-terminal D2 domain is followed by a short tether of 5-12 amino acids in length before the beginning of the transmembrane helix. 

Fig. 4. Schematic illustration of chemokine-receptor interactions. The transmembrane helices of the receptor, shown as blue tubes, were derived from the structure of rhodopsin (PDB code 1L9H). The chemokine (pink) and the N-terminal extracellular domain of the receptor were derived from the IL8-CXCR1 peptide complex shown in Fig. 5 (PDB code lILP). Except for the N-terminus, the loops of the receptor are not displayed. The figure illustrates the relative size of the receptor and ligand, and the interaction of the receptor N-terminus along one face of the chemokine. The interaction orients the N-terminal signal domain towards the receptor as displayed here it is oriented towards the helical bundle, which may or may not be correct for some chemokines. (See Color Insert.)...

Epithelial cadherin (E-cadherin) has a molecular weight of 130 kDa and is found in PNS myelin. E-cadherin is a protein of the superfamily of calcium-dependent cell adhesion molecules that can usually form adherent junctions. This protein has an N-terminal extracellular domain, a short transmembrane domain and a C-terminal intracellular domain. 

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