-X-C-X2-(S/T)-X3-P-X-C-D-G-(S/A/T)-H is a defining feature of this unique family of proteins and is likely involved in ironbinding. Localization studies demonstrate that mitoNEET is an integral protein present in the outer mitochondrial membrane. An amino-terminal anchor sequence tethers the protein to the outer membrane with the CDGSH domain oriented toward the cytoplasm. Cardiac mitochondria isolated from mitoNEET-null mice demonstrate a reduced oxidative capacity, suggesting that mito-NEET is an important iron-containing protein involved in the control of maximal mitochondrial respiratory rates. mitochondria ͉ oxidative phosphorylation ͉ pioglitazone

Acarbose improved long-term glycemic control in patients with non-insulin-dependent diabetes mellitus regardless of concomitant antidiabetic medication.

The endosomal compartment of polarized epithelial cells is a major crossroads for membrane traffic. Proteins entering this compartment from the cell surface are sorted for transport to one of several destinations: recycling to the original cell surface, targeting to lysosomes for degradation, or transcytosis to the opposite surface. The polymeric immunoglobulin receptor (pIgR), which is normally transcytosed from the basolateral to the apical surface, was used as a model to dissect the signals that mediate this sorting event. When exogenous receptor was expressed in Madin-Darby Canine Kidney (MDCK) cells, it was shown that phosphorylation of pIgR at the serine residue at position 664 is required for efficient transcytosis. Replacement of this serine with alanine generated a receptor that is transcytosed only slowly, and appears to be recycled. Conversely, substitution with aspartic acid (which mimics the negative charge of the phosphate group) results in rapid transcytosis. It was concluded that phosphorylation is the signal that directs the pIgR from the endosome into the transcytotic pathway.

Conscious patients with Grade III fourth ventricular compression should undergo urgent clot evacuation before deterioration. Surgical evacuation of the clot may not be required for large hematomas (>3 cm) if the fourth ventricle is not totally obliterated at the level of the clot.

A novel membrane aminopeptidase has been identified as a major protein in vesicles from rat adipocytes containing the glucose transporter isotype Glut4. In this study we have characterized this aminopeptidase, referred to as vp165, in 3T3-L1 adipocytes. The subcellular distributions of vp165 and Glut4 were determined by immunoisolation of vesicles with antibodies against both proteins, by immunofluorescence, and by subcellular fractionation and immunoblotting. Relative amounts of vp165 at the cell surface in basal and insulin-treated cells were assayed by cell surface biotinylation. These experiments showed that vp165 and Glut4 were entirely colocalized and that vp165 increased markedly at the cell surface in response to insulin, in a way similar to Glut4. When intact cells were assayed with a novel, membrane-impermeant fluorogenic substrate for vp165, we found that insulin stimulated aminopeptidase activity at the cell surface. This observation provides direct evidence for the functional consequence of vp165 translocation.An important effect of insulin is to increase glucose transport into muscle and fat cells. The basis of this effect is an increase in the amount of the glucose transporter isotype Glut4 in the plasma membrane, which is probably largely due to insulinelicited fusion of intracellular vesicles containing Glut4 with the plasma membrane (1, 2). We and others have developed methods for isolating these Glut4 vesicles from fat and muscle cells and are analyzing the proteins in them (3-6). A major protein, of 165 kDa, in the Glut4 vesicles from rat adipocytes (designated vp165) has recently been characterized by the Pilch laboratory and ourselves (3,7,8). Through cloning of the cDNA for vp165, we found that it is a novel membrane aminopeptidase, consisting of a 109 residue cytoplasmic amino-terminal domain that contains several potential sorting signals similar to those in Glut4, a single transmembrane segment, and a large lumenal domain that contains the active site (9).The distribution of vp165 in rat adipocytes has been determined for basal and insulin-treated cells by subcellular fractionation and immunoblotting (3, 7). These earlier studies showed that vp165, like Glut4, is concentrated in the low density microsomes and redistributes to the plasma membrane in response to insulin. Moreover, they showed that intracellular vp165 is located in vesicles that also contain Glut4, since immunoadsorption of vesicles with antibodies against Glut4 also adsorbed most of the vp165 (3, 7). However, these earlier studies did not rigorously address the questions of whether vp165 and Glut4 are entirely colocalized and translocate in a quantitatively similar way in response to insulin. One reason for this is that subcellular fractionation provides only a crude indication of subcellular localization and typically underestimates translocation due to contamination of the plasma membrane fraction with intracellular membranes (see Results and Discussion). Also, since at the time antibodies that immunoadsorbed vp165 were...