The Golgi-localized Arabidopsis endomembrane protein12 contains both endoplasmic reticulum export and Golgi retention signals at its C terminus

Endomembrane proteins (EMPs), belonging to the evolutionarily conserved transmembrane nine superfamily in yeast and mammalian cells, are characterized by the presence of a large lumenal N terminus, nine transmembrane domains, and a short cytoplasmic tail. The Arabidopsis thaliana genome contains 12 EMP members (EMP1 to EMP12), but little is known about their protein subcellular localization and function. Here, we studied the subcellular localization and targeting mechanism of EMP12 in Arabidopsis and demonstrated that (1) both endogenous EMP12 (detected by EMP12 antibodies) and green fluorescent protein (GFP)-EMP12 fusion localized to the Golgi apparatus in transgenic Arabidopsis plants; (2) GFP fusion at the C terminus of EMP12 caused mislocalization of EMP12-GFP to reach post-Golgi compartments and vacuoles for degradation in Arabidopsis cells; (3) the EMP12 cytoplasmic tail contained dual sorting signals (i.e., an endoplasmic reticulum export motif and a Golgi retention signal that interacted with COPII and COPI subunits, respectively); and (4) the Golgi retention motif of EMP12 retained several post-Golgi membrane proteins within the Golgi apparatus in gain-of-function analysis. These sorting signals are highly conserved in all plant EMP isoforms and, thus, likely represent a general mechanism for EMP targeting in plant cells.     

Estimating incident population distribution from prevalent data

A prevalent sample consists of individuals who have experienced disease incidence but not failure event at the sampling time. We discuss methods for estimating the distribution function of a random vector defined at baseline for an incident disease population when data are collected by prevalent sampling. Prevalent sampling design is often more focused and economical than incident study design for studying the survival distribution of a diseased population, but prevalent samples are biased by design. Subjects with longer survival time are more likely to be included in a prevalent cohort, and other baseline variables of interests that are correlated with survival time are also subject to sampling bias induced by the prevalent sampling scheme. Without recognition of the bias, applying empirical distribution function to estimate the population distribution of baseline variables can lead to serious bias. In this article, nonparametric and semiparametric methods are developed for distribution estimation of baseline variables using prevalent data.     

Long-term results in patients after rectosigmoid vaginoplasty

Many methods are used for vaginoplasty, including the split-thickness skin graft, full-thickness skin graft, and inverted penile skin flap. However, these procedures are not entirely satisfactory in cases of reconstructed vaginal stenosis, inadequate vaginal length, or poor lubrication. The small intestine, ascending colon, and sigmoid colon can be used in the intestinal flap method, and the authors modified the operation first described by Baldwin in which a loop of rectosigmoid is isolated, closed at one end, and brought down on its vascular pedicle as a neovagina and then anastomosed to the perineum.Vaginoplasty using the rectosigmoid was performed in 36 patients (28 male-to-female transsexual patients, five patients with congenital vaginal atresia, and three with cervical cancer). The follow-up period ranged from 1 to 10 years. The postoperative results were analyzed through physical examination and interview regarding the patient's functional status and satisfaction during sexual intercourse. The mean depth and width of the vaginal cavity were 12.5 cm and 3.9 cm, respectively. Excessive mucosal discharge was seen in 8.3 percent, and malodor was found in 8.3 percent. All patients who had partners were able to have sexual intercourse; 2.8 percent of patients used lubricants and 5.6 percent used dilators before intercourse for more than a year postoperatively. During intercourse, 88.9 percent of the patients experienced orgasm. The cosmetic and functional results of rectosigmoid vaginoplasty were excellent. Thus, the advantages of rectosigmoid vaginoplasty are (1) rare contraction of the reconstructed vagina, (2) vaginal width and depth maintained without long-term vaginal stent, (3) spontaneous mucus production facilitating sexual intercourse, (4) avoidance of the malodor frequently accompanying skin graft, and (5) texture and appearance similar to that of the natural vagina. The authors concluded that rectosigmoid vaginoplasty is the best choice for transsexual patients who have previously undergone penectomy and orchiectomy, patients with unfavorable previous vaginoplasty, those with short vaginal length after cervical cancer surgery, and patients with congenital vaginal atresia.     

Effect of self-association on the structural organization of partially folded proteins: inactivated actin

The propensity to associate or aggregate is one of the characteristic properties of many nonnative proteins. The aggregation of proteins is responsible for a number of human diseases and is a significant problem in biotechnology. Despite this, little is currently known about the effect of self-association on the structural properties and conformational stability of partially folded protein molecules. G-actin is shown to form equilibrium unfolding intermediate in the vicinity of 1.5 M guanidinium chloride (GdmCl). Refolding from the GdmCl unfolded state is terminated at the stage of formation of the same intermediate state. An analogous form, known as inactivated actin, can be obtained by heat treatment, or at moderate urea concentration, or by the release of Ca(2+). In all cases actin forms specific associates comprising partially folded protein molecules. The structural properties and conformational stability of inactivated actin were studied over a wide range of protein concentrations, and it was established that the process of self-association is rather specific. We have also shown that inactivated actin, being denatured, is characterized by a relatively rigid microenvironment of aromatic residues and exhibits a considerable limitation in the internal mobility of tryptophans. This means that specific self-association can play an important structure-forming role for the partially folded protein molecules.     

Aorta protein networks in marginal and acute zinc deficiency

Human zinc deficiency is a global problem and may influence the development of cardiovascular disease. Our objective was to determine Zn deficiency affected pathways and protein interactions in rat aorta and their likely influence on stress-induced atherogenesis. In two separate studies, rats were given diets acutely (<1 mg Zn/kg) or marginally (6 mg Zn/kg) deficient in Zn. Both studies included Zn adequate controls (35 mg Zn/kg) and the acute deficiency study included a pair-fed group. After 6 wk, proteins from thoracic aorta were separated by 2-DE. Proteins affected by zinc deficiency were identified by principal component analysis. Multiple correlations of identified proteins indicated protein networks of related function. Proteins clusters decreased in zinc deficiency were related to fatty acid and carbohydrate metabolism. Structurally related proteins, including zyxin and over nine transgelin 1 proteins, were either increased or decreased by acute and marginal deficiencies. PKC alpha was significantly decreased in Zn deficiency suggesting that Zn may regulate the phosphorylation of target proteins. Zn deficiency-related changes in structural, carbohydrate and fatty acid-related proteins may be disadvantageous for maintaining vascular health and are consistent with a protective role for zinc in the development of atherosclerosis.