ALIS are stress-induced protein storage compartments for substrates of the proteasome and autophagy.

Misfolded proteins can be directed into cytoplasmic aggregates such as aggresomes and dendritic cell aggresome-like induced structures (DALIS). DALIS were originally identified in lipopolysaccharide-stimulated dendritic cells and act as storage compartments for polyubiquitinated Defective Ribosomal Products (DRiPs) prior to their clearance by the proteasome. Here we demonstrate that ubiquitinated protein aggregates that are similar to DALIS, and not related to aggresomes, can be observed in several cell types in response to stress, including oxidative stress, transfection, and starvation.

In situ imaging and isolation of proteins using dsDNA oligonucleotides.

As proteomics initiatives mature, the need will arise for the multiple visualization of proteins and supramolecular complexes within their true context, in situ. Single-stranded DNA and RNA aptamers can be used for low resolution imaging of cellular receptors and cytoplasmic proteins by light microscopy (LM). These techniques, however, cannot be applied to the imaging of nuclear antigens as these single-stranded aptamers bind endogenous RNA and DNA with high affinity.

Application of quantum dots as probes for correlative fluorescence, conventional, and energy-filtered transmission electron microscopy.

Luminescent semiconductor quantum dots (QDs) are a new class of fluorescent label with wide-ranging applications for cell imaging. The electron density and elemental composition of these materials permit the extension of their use as probes in conventional electron microscopy (TEM) and energy-filtered TEM (EFTEM). Here we illustrate the feasibility of using streptavidin-conjugated QDs as TEM tags by labeling a nuclear protein on cell sections and obtaining correlative fluorescence and TEM data.