Mechanical strength of specific bonds acting isolated or in pairs: a case study on engineered proteins.

The dynamic strength of multiple specific bonds exposed to external mechanical force is of significant interest for the understanding of biological adhesion. Exploiting the well-established FLAG tag technology, we engineered model proteins exhibiting no, one, or two identical binding sites for a monoclonal antibody. Bonds between these engineered proteins and the antibody were studied with dynamic force spectroscopy.

Tyrosine phosphorylation of vinculin at position 1065 modifies focal adhesion dynamics and cell tractions.

Focal adhesions (FAs) connect the cellular actin cytoskeleton via integrin with the extracellular matrix. They comprise of many structural and signaling proteins which are highly dynamic, well regulated, and responsible for the sensing of physical properties from the environment. Vinculin is a protein that incorporates all these functions.

Probing biomembrane dynamics by dual-wavelength reflection interference contrast microscopy.

We present an improved analysis of reflection interference contrast microscopy (RICM) images, recorded to investigate model membrane systems that mimic cell adhesion. The model systems were giant unilamellar vesicles (GUV) adhering via specific ligand-receptor interactions to supported lipid bilayers (SLB) or to patterns of receptors. Conventional RICM and dual-wavelength RICM (DW-RICM) were applied to measure absolute optical distances between the biomembranes and planar substrates.

Presenilin 1 affects focal adhesion site formation and cell force generation via c-Src transcriptional and posttranslational regulation.

Presenilin 1 and 2 (PS) are critical components of the gamma-secretase complex that cleaves type I transmembrane proteins within their transmembrane domains. This process leads to release of proteolytically processed products from cellular membranes and plays an essential role in signal transduction or vital functions as cell adhesion. Here we studied the function of presenilins in cell-matrix interaction of wild-type and PS knock-out mouse embryonic fibroblasts.

Toward physiological conditions for cell analyses: forces of heart muscle cells suspended between elastic micropillars.

Almost each mammalian cell permanently applies forces to its environment. These forces are essential for many vital processes such as tissue formation or cell movement. In turn, the environmental conditions of cells strongly affect force production.