ERGIC-53 KKAA signal mediates endoplasmic reticulum retrieval in yeast.

Studies on the ERGIC-53 KKAA signal have revealed a new mechanism for static retention of mammalian proteins in the endoplasmic reticulum (Andersson, H., Kappeler, F., Hauri, H.

Cell adhesion to a population of laminin isoforms isolated from normal renal tissue.

To assess whether cells react differently towards a population of several laminin isoforms, as found in vivo, vs. a single isoform, we have compared the biological activity of kidney laminins to that of pure laminin 1. The kidney laminin preparation contained laminin 1 and further isoforms.

The ADP-ribosylation factor GTPase-activating protein Glo3p is involved in ER retrieval.

Retrograde transport of proteins from the Golgi to the endoplasmic reticulum (ER) has been the subject of some interest in the recent past. Here a new thermosensitive yeast mutant defective in retrieval of dilysine-tagged proteins from the Golgi back to the endoplasmic reticulum was characterized. The ret4-1 mutant also exhibited a selective defect in forward ER-to-Golgi transport of some secreted proteins at the non-permissive temperature.

Targeting of cytoskeletal linker proteins to focal adhesion complexes is reduced in fibroblasts adhering to laminin-1 when compared to fibronectin.

Cellular interactions with the extracellular matrix determine to a large extent cell behavior, including cell migration. These interactions take place at specialized cellular structures, the focal adhesions, which have a substrate-specific morphology. To determine the molecular and functional relevance of this observation, the composition of isolated focal adhesions developed by fibroblasts adhering to fibronectin or laminin-1 was analyzed by indirect immunofluorescence and immunoblotting with or without stabilization of the structures by cross-linking.

Impaired mechanical stability, migration and contractile capacity in vimentin-deficient fibroblasts.

Loss of a vimentin network due to gene disruption created viable mice that did not differ overtly from wild-type littermates. Here, primary fibroblasts derived from vimentin-deficient (-/-) and wild-type (+/+) mouse embryos were cultured, and biological functions were studied in in vitro systems resembling stress situations. Stiffness of -/- fibroblasts was reduced by 40% in comparison to wild-type cells.

Cell adhesion to laminin 1 or 5 induces isoform-specific clustering of integrins and other focal adhesion components.

Laminin 1 (alpha1beta1gamma1) and laminin 5 (alpha3beta3gamma2) induce cell adhesion with different involvement of integrins: both are ligands for the alpha6beta1 integrin, while alpha3beta1 integrin has affinity for laminin 5 only. These two laminin isoforms therefore provide good models to investigate whether alpha3beta1 and alpha6beta1 integrins play different roles in signal transduction and in focal adhesion formation. Laminin 1 or 5 induced adhesion of normal human skin fibroblasts to a similar extent but promoted different overall cell shapes.