The biogenesis of membrane proteins with a single transmembrane (TM) segment is well understood. However, understanding the biogenesis and membrane assembly of membrane proteins with multiple TM segments is still incomplete because of the complexity and diversity of polytopic membrane proteins. In an attempt to investigate further the biogenesis of polytopic membrane proteins, I used the human ...

It is thought that the topology of a polytopic protein is generated by sequential translocation and membrane integration of independent signal-anchor and stop-transfer sequences. Two well-characterized cell-free systems (rabbit reticulocyte lysate and wheat germ extract) have been widely used to study the biogenesis of secretory and membrane proteins, but different results have been observed wi...

Discontinuous Galerkin (dG) methods on meshes consisting of polygonal/polyhedral (henceforth, collectively termed as polytopic) elements have received considerable attention in recent years. Due to the physical frame basis functions used typically and quadrature challenges involved, matrix-assembly step for these is often computationally cumbersome. To address this important practical issue, wo...

Soluble proteins often contain multiple structural domains, which are shuffled or recombined to gain new functions in the course of evolution. We examined integral membrane proteins for evidence of this mechanism using a classification of polytopic transmembrane domains. Surprisingly, in contrast to the situation in aqueous solution, we found that recombination of structural domains is not comm...

The signal recognition particle (SRP) targeting pathway is required for the efficient insertion of many polytopic inner membrane proteins (IMPs) into the Escherichia coli inner membrane, but in the absence of SRP protein export proceeds normally. To define the properties of IMPs that impose SRP dependence, we analyzed the targeting requirements of bitopic IMPs that are structurally intermediate...

Endoplasmic reticulum-associated degradation (ERAD) plays a critical role in the destruction of terminally misfolded proteins at the secretory pathway. The system also regulates expression levels of several proteins such as Pca1p, a cadmium exporter in yeast. To gain better insight into the mechanisms underlying ERAD of Pca1p and other polytopic proteins by the proteasome in the cytosol, our st...

The aim of this paper is to transform the model of the impedance controlled robot interaction with feedback delay to a Tensor Product (TP) type polytopic LPV model whereupon Linear Matrix Inequality (LMI) based control design can be immediately executed. The paper proves that the impedance model can be exactly represented by a finite element TP type polytopic model under certain constrains. The...