@article {49739, title = {Distinct Rap1 activity states control the extent of epithelial invagination via α-catenin.}, journal = {Dev Cell}, volume = {25}, year = {2013}, month = {2013 May 13}, pages = {299-309}, abstract = {

Localized cell shape change initiates epithelial folding, while neighboring cell invagination determines the final depth of an epithelial fold. The mechanism that controls the extent of invagination remains unknown. During Drosophila gastrulation, a higher number of cells undergo invagination to form the deep posterior dorsal fold, whereas far fewer cells become incorporated into the initially very similar anterior dorsal fold. We find that a decrease in α-catenin activity causes the anterior fold to invaginate as extensively as the posterior fold. In contrast, constitutive activation of the small GTPase Rap1 restricts invagination of both dorsal folds in an α-catenin-dependent manner. Rap1 activity appears spatially modulated by Rapgap1, whose expression levels are high in the cells that flank the posterior fold but low in the anterior fold. We propose a model whereby distinct activity states of Rap1 modulate α-catenin-dependent coupling between junctions and actin to control the extent of epithelial invagination.

}, keywords = {Actins, alpha Catenin, Animals, Cell Adhesion, Cell Adhesion Molecules, Cell Membrane, Cell Shape, Drosophila, Drosophila Proteins, Embryo, Nonmammalian, Enzyme Activation, Epithelial Cells, Genes, Insect, Green Fluorescent Proteins, GTP Phosphohydrolases, GTPase-Activating Proteins, Intercellular Junctions, RNA Interference, Time factors, Time-Lapse Imaging}, issn = {1878-1551}, doi = {10.1016/j.devcel.2013.04.002}, author = {Wang, Yu-Chiun and Khan, Zia and Wieschaus, Eric F} } @article {49775, title = {Archaeosortases and exosortases are widely distributed systems linking membrane transit with posttranslational modification.}, journal = {J Bacteriol}, volume = {194}, year = {2012}, month = {2012 Jan}, pages = {36-48}, abstract = {

Multiple new prokaryotic C-terminal protein-sorting signals were found that reprise the tripartite architecture shared by LPXTG and PEP-CTERM: motif, TM helix, basic cluster. Defining hidden Markov models were constructed for all. PGF-CTERM occurs in 29 archaeal species, some of which have more than 50 proteins that share the domain. PGF-CTERM proteins include the major cell surface protein in Halobacterium, a glycoprotein with a partially characterized diphytanylglyceryl phosphate linkage near its C terminus. Comparative genomics identifies a distant exosortase homolog, designated archaeosortase A (ArtA), as the likely protein-processing enzyme for PGF-CTERM. Proteomics suggests that the PGF-CTERM region is removed. Additional systems include VPXXXP-CTERM/archeaosortase B in two of the same archaea and PEF-CTERM/archaeosortase C in four others. Bacterial exosortases often fall into subfamilies that partner with very different cohorts of extracellular polymeric substance biosynthesis proteins; several species have multiple systems. Variant systems include the VPDSG-CTERM/exosortase C system unique to certain members of the phylum Verrucomicrobia, VPLPA-CTERM/exosortase D in several alpha- and deltaproteobacterial species, and a dedicated (single-target) VPEID-CTERM/exosortase E system in alphaproteobacteria. Exosortase-related families XrtF in the class Flavobacteria and XrtG in Gram-positive bacteria mark distinctive conserved gene neighborhoods. A picture emerges of an ancient and now well-differentiated superfamily of deeply membrane-embedded protein-processing enzymes. Their target proteins are destined to transit cellular membranes during their biosynthesis, during which most undergo additional posttranslational modifications such as glycosylation.

}, keywords = {Amino Acid Sequence, Aminoacyltransferases, Archaeal Proteins, Bacterial Proteins, Cell Membrane, Cysteine Endopeptidases, Gene Expression Regulation, Archaeal, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Molecular Sequence Data, Protein Processing, Post-Translational}, issn = {1098-5530}, doi = {10.1128/JB.06026-11}, author = {Haft, Daniel H and Payne, Samuel H and Selengut, Jeremy D} } @article {38119, title = {Archaeosortases and exosortases are widely distributed systems linking membrane transit with posttranslational modification}, journal = {Journal of bacteriologyJournal of bacteriology}, volume = {194}, year = {2012}, note = {http://www.ncbi.nlm.nih.gov/pubmed/22037399?dopt=Abstract}, type = {10.1128/JB.06026-11}, abstract = {Multiple new prokaryotic C-terminal protein-sorting signals were found that reprise the tripartite architecture shared by LPXTG and PEP-CTERM: motif, TM helix, basic cluster. Defining hidden Markov models were constructed for all. PGF-CTERM occurs in 29 archaeal species, some of which have more than 50 proteins that share the domain. PGF-CTERM proteins include the major cell surface protein in Halobacterium, a glycoprotein with a partially characterized diphytanylglyceryl phosphate linkage near its C terminus. Comparative genomics identifies a distant exosortase homolog, designated archaeosortase A (ArtA), as the likely protein-processing enzyme for PGF-CTERM. Proteomics suggests that the PGF-CTERM region is removed. Additional systems include VPXXXP-CTERM/archeaosortase B in two of the same archaea and PEF-CTERM/archaeosortase C in four others. Bacterial exosortases often fall into subfamilies that partner with very different cohorts of extracellular polymeric substance biosynthesis proteins; several species have multiple systems. Variant systems include the VPDSG-CTERM/exosortase C system unique to certain members of the phylum Verrucomicrobia, VPLPA-CTERM/exosortase D in several alpha- and deltaproteobacterial species, and a dedicated (single-target) VPEID-CTERM/exosortase E system in alphaproteobacteria. Exosortase-related families XrtF in the class Flavobacteria and XrtG in Gram-positive bacteria mark distinctive conserved gene neighborhoods. A picture emerges of an ancient and now well-differentiated superfamily of deeply membrane-embedded protein-processing enzymes. Their target proteins are destined to transit cellular membranes during their biosynthesis, during which most undergo additional posttranslational modifications such as glycosylation.}, keywords = {Amino Acid Sequence, Aminoacyltransferases, Archaeal Proteins, Bacterial Proteins, Cell Membrane, Cysteine Endopeptidases, Gene Expression Regulation, Archaeal, Gene Expression Regulation, Bacterial, Gene Expression Regulation, Enzymologic, Molecular Sequence Data, Protein Processing, Post-Translational}, author = {Haft, Daniel H. and Payne, Samuel H. and J. Selengut} } @article {49628, title = {Detection of alloantigens during preimplantation development and early trophoblast differentiation in the mouse by immunoperoxidase labeling.}, journal = {J Exp Med}, volume = {143}, year = {1976}, month = {1976 Feb 1}, pages = {348-59}, abstract = {

An immunoperoxidase-labeling technique allowing visualization of antibody binding to the cell surface at the electron microscopical level has been employed an an analysis of H-2 and non-H-2 alloantigen expression on the early mouse embryo. The presence of non-H-2 antigenic determinants has been confirmed on eight-cell, morula, and blastocyst stages of development. Contrary to previous reports, however, low levels of H-2 antigen have also been detected on the blastocyst. This is the earliest stage at which H-2 has been shown to be expressed on the fertilized mouse egg and may reflect the greater resolution of the immunoperoxidase technique. Using two different models to study the critical peri-implantation stages, those of experimentally induced blastocyst activation and blastocyst outgrowth in vitro, it has been demonstrated that antigen loss occurs on the trophectoderm at the time of implantation, and that this is not necessarily dependent upon maternal influence. It is suggested that the loss may be an important factor in the prevention of maternal immune rejection during the establishment of the fetal allograft. The two major components of the early postimplantation conceptus display a striking differential in antigenic status. The embryonic sac shows a high degree of peroxidase labeling, while the ectoplacental cone trophoblast is unlabeled. These findings add support to the concept of antigenic neutrality of the early trophoblast and its role in the maintenance of a normal fetomaternal immunological equilibrium.

}, keywords = {Animals, Binding Sites, Antibody, Blastocyst, Cell Differentiation, Cell Membrane, Embryo Implantation, Embryonic Development, Epitopes, Female, Histocompatibility Antigens, HLA Antigens, Horseradish Peroxidase, Mice, Mice, Inbred Strains, Pregnancy, Pregnancy, Animal, Trophoblasts}, issn = {0022-1007}, author = {Searle, R F and Sellens, M H and Elson, J and Jenkinson, E J and Billington, W D} }