Single-transmembrane segment

These interactions involve adhesion proteins called selectins, which are found both on the rolling leukocytes and on the endothelial cells of the vascular walls. Selectins have a characteristic domain structure, consisting of an N-terminal extracellular lectin domain, a single epidermal growth factor (EGR) domain, a series of two to nine short consensus repeat (SCR) domains, a single transmembrane segment, and a short cytoplasmic domain. Lectin domains, first characterized in plants, bind carbohydrates... 

This minimal K+ channel (MinK) encoded by KCNEl consists of 130 amino acid residues and has a single transmembrane segment. A slowly activating K+ current-induced MinK cRNA is expressed in Xenopus oocytes. Coexpression of KvLQTl with MinK induced a current that has characteristics similar to cardiac slowly activating delayed-rectifier K+ current, DCS, in contrast to DCR that has relative fast activation and is composed of hERG/MiRPl. 

Ca2+ channels [19] and functions as a tetramer of four separate subunits, analogous to the structure of Na+ and Ca2+ channels (Fig. 6-7B). Like the Na+ channels and the Ca2+ channels, the K+ channels have auxiliary subunits, which include intracellularly located p subunits as well as minK or minK-related subunits having a single transmembrane segment [19,20],... 

The leptin signal is transduced by a mechanism also used by receptors for interferon and growth factors, the JAIC-STAT system (Fig. 23-34 see Fig. 12-9). The leptin receptor, which has a single transmembrane segment, dimerizes when leptin binds to the extracellular domain of two monomers. Both monomers are phos-phorylated on a Tyr residue of the intracellular domain by a Janus kinase (JAK). The -Tyr residues become docking sites for three proteins that are signal transducers and activators of transcription (STATs 3, 5, and 6, sometimes called fat-STATS). The docked STATs are then phosphorylated on Tyr residues by the... 

Figure 5 Proposed model for the HFE protein. The model was constructed by homology to other MHC class 1 proteins. The protein has three extraceUular domains, which are homologous to the i, 2, and q 3 domains of other MHC class 1 proteins. The protein also has a site for noncovalent interaction with Pi microglobulin, which is a separate protein. In addition, the protein has a single transmembrane segment and a short c)doplasmic tail...

Bayley H (1994) Channels with single transmembrane segments. In News Physiol Sci 9 45. 

Guanylyl Cyclases with a Single Transmembrane Segment... 

We tested pref 2.0 in predicting transmembrane segments for (3-strand proteins on the data set consisting ofsrxporin (ompf ecoh, pori rhoca, ompa ecoli, om32 comac, phoe ecoli, lamb ecoli) and one defensin (defn human), and found that PREF 2.0 predicts no single transmembrane segment. 

Group 1, Single-transmembrane segment catalytic receptors. 

Wozniak, R. W., and Blobel, G. (1992). The single transmembrane segment of gp210 is sufflcient for sorting to the pore membrane domain of the nuclear envelope. J. Cell BioL 119,1441-1451. 

There are also three isoforms of the B subunit 61, 62, and B3. Presumably, each isoform is expressed along with its a partner and assembled in the endoplasnric reticulum as an a-6 heterodimer. The B subunit has a single transmembrane segment and is a type II membrane protein, with the N-terminal cytoplasmic and the C-terminal sequence extracytoplasmic. There are three N-linked glycosylation consensus sequences (NXT or NXS) and three disulfide bonds in the extracytoplasmic domain of the B subunit. The function of the 6 subunit of this ATPase is not very clear. Alteration of its structure by disulfide reduction inhibits ATPase activity. In its absence, the a subunit is unstable and does not reach the plasma membrane, so it is required for structural stability. Why the a subunit is unstable in the absence of the B subunit is not obvious, because the plasma membrane Ca ATPase has similar topology but does not require a B subunit for stable plasma membrane expression. It seems that membrane insertion of the M5 and subsequent domains depends on expression of the B subunit. Only the K countertransport pumps require a B subunit, and modification of this protein modifies pump kinetics. 

The majority of receptors affecting acid secretion belong to the G7 (seven transmembrane segments) class of receptors (H2, muscarinic, CCK2, somatostatin, prostaglandin). The EGF/TGF-a receptor, which also inhibits acid secretion, is a tyrosine kinase receptor (single transmembrane segment with an intracellular ATP kinase domain). 

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