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Scientists from IRB Barcelona, IBMB-CSIC and BSC discover a new method for innocuous protein tagging

The Institute for Research in Biomedicine (IRB Barcelona) and the Molecular Biology Institute of Barcelona (IBMB-CSIC), both of which are based at the Parc Científic de Barcelona, in collaboration with the Barcelona Supercomputing Center (BSC) and the University of Barcelona (UB), take part in a study that provides a new approach to follow cellular proteins more closely.

The study performed at the premises of Parc Científic de Barcelona, home to both participating research institutes, has revealed a new method for protein tagging that preserves protein native functions and structure.


The study, published today at Nature Methods, the most prestigious journal for the presentation of results in methods development, proposes the use of two plant protein epitopes (a type of antigen), named inntags, as the most innocuous and stable tagging tools in the study of physical and functional interactions of proteins.


Proteins and peptides of various sizes and shapes have been used since the early 80s to tag proteins with many different purposes, ranging from purification fluorescence-based microscopic detection in whole organisms. However, tagging strategies used nowadays run the risk that the native function of the protein may be abolished or compromised by interactions with the tag.


A study led by researchers from the Molecular Biology Institute of Barcelona of the CSIC, the Joint Programme for Computational Biology  of the Institute for Research in Biomedicine (IRB Barcelona) and the Barcelona SuperComputing Center (BSC), and the University of Barcelona, ​​has analyzed the available list of polypeptides  with known 3D structure to identify among them the most suitable for tagging purposes.


Researchers have selected the smallest protein domains that still display strong structural determinants to act as antigens, do not generate solubility issues, do not compromise cell fitness and cause no detectable functional or localization effects when fused to other target proteins.


Researchers first used a series of bioinformatics tools to scan through the entire proteome to select which proteins could, in principle, have good tagging properties.  After manual curation of the s in silico results, 12 tag candidates were tested in vivo, finding excellent or outstanding properties for all of them. Inntags maintain their integrity, stability, solubility in cell extracts, diffusional mobility and do not cause important functional perturbations that commonly used tags-such as MYC, FLAG or HA do cause.

The developed technology will open new possibilities for researchers in cellular biology, as they will provided them a neater, unbiased method to track proteins inside the cell.