Thomas Wieland

A fluorescent derivative of phalloidin has been synthesized possessing high affinity to filamentous actin. This compound was used for visualization of actin-containing structures in eukaryotic nonmuscle cells. Due to its low molecular weight (1250), fixation for formaldehyde was sufficient to render the membrane permeable for the labeled peptide. Bundles of microfilaments are the predominant pattern in the flat rat kangaroo PtK1 cells, whereas a net of concentric fibers characterizes the more spherical bovine kidney MDBK cells. Specificity of staining was confirmed by competition experiments with unlabeled phalloidin.

Genome-, transcriptome- and proteome-wide measurements provide insights into how biological systems are regulated. However, fundamental aspects relating to which human proteins exist, where they are expressed and in which quantities are not fully understood. Therefore, we generated a quantitative proteome and transcriptome abundance atlas of 29 paired healthy human tissues from the Human Protein Atlas project representing human genes by 18,072 transcripts and 13,640 proteins including 37 without prior protein-level evidence. The analysis revealed that hundreds of proteins, particularly in testis, could not be detected even for highly expressed mRNAs, that few proteins show tissue-specific expression, that strong differences between mRNA and protein quantities within and across tissues exist and that protein expression is often more stable across tissues than that of transcripts. Only 238 of 9,848 amino acid variants found by exome sequencing could be confidently detected at the protein level showing that proteogenomics remains challenging, needs better computational methods and requires rigorous validation. Many uses of this resource can be envisaged including the study of gene/protein expression regulation and biomarker specificity evaluation.