Isolation Protocols | Protein | Molecular Biology

Tandem RNA and Protein Extraction: A Platform for Maximizing the Use of Limited Ex Vivo Tissue Samples

CK Ciarán Kennedy

BM Braden Millar

LC Luke J. Conroy

MM Mariam Marai

MB Mary Barry

MO Martin O’Donohoe [...]

Md Monica de Gaetano

+ 3 Authors

0 Q&A

343 Views

Mar 20, 2026

Human tissue samples represent the gold standard for obtaining clinically relevant and translatable insight into disease processes that in vitro systems cannot fully reproduce. However, patient-derived samples are often limited in size and availability, limiting the number of downstream assays that can be performed. To maximize the use of invaluable human samples, we present a protocol for the tandem extraction of high-quality RNA and protein from the same tissue section. This method has been optimized for 15–30 mg tissue sections, enabling more experimental conditions and technical replicates, while minimizing intrasample variability associated with heterogeneous tissues. This protocol also avoids potentially hazardous solvents present in phenol-chloroform-based methods such as TRIzol, providing a safer and more accessible workflow without compromising biomolecule integrity. This protocol was developed and validated using atherosclerotic plaque tissue from carotid endarterectomy, a very challenging tissue type to work with due to extensive calcification, necrosis, and limited surgical availability. We have also validated this method using mouse aortic tissue and cultured THP-1 cells, demonstrating its versatility across sample input types. As this protocol relies on standard column-based RNA extraction kits and commonly available reagents for protein precipitation and extraction, this methodology is widely accessible and easy to implement as a standard, streamlined workflow.

Mouse Adipose Tissue Protein Extraction

YA Yu A. An

PS Philipp E. Scherer

0 Q&A

15986 Views

Jun 5, 2020

As obesity becomes a global epidemic, the metabolism research field is increasingly focusing on studying the physiological and pathological roles of adipose tissues (AT). However, extracting proteins from AT is challenging due to abundant fat content of intracellular lipid droplets. Several commercial kits for extraction of AT proteins are available, as are protocols (such as the RELi protocol as well as other protein precipitation protocols). The protocols have been introduced to improve the quality and yield of extractions, but these methods either increase the cost or involve multiple steps. Herein, we describe a detailed protocol for mouse AT protein extractions based on our daily laboratory practice. This protocol requires only very common reagents and instruments, and can be completed in 90-120 min and provides good recovery of total protein content. Thus, this protocol is an economically attractive, time-saving and efficient way to extract proteins from the AT.

Purification of Protein-complexes from the Cyanobacterium Synechocystis sp. PCC 6803 Using FLAG-affinity Chromatography

MK Minna M. Koskela

PS Petra Skotnicová

ÉK Éva Kiss

RS Roman Sobotka

0 Q&A

6260 Views

May 20, 2020

Exploring the structure and function of protein complexes requires their isolation in the native state–a task that is made challenging when studying labile and/or low abundant complexes. The difficulties in preparing membrane-protein complexes are especially notorious. The cyanobacterium Synechocystis sp. PCC 6803 is a widely used model organism for the physiology of oxygenic phototrophs, and the biogenesis of membrane-bound photosynthetic complexes has traditionally been studied using this cyanobacterium. In a typical approach, the protein complexes are purified with a combination of His-affinity chromatography and a size-based fractionation method such as gradient ultracentrifugation and/or native electrophoresis. However, His-affinity purification harbors prominent contaminants and the levels of many proteins are too low for a feasible multi-step purification. Here, we have developed a purification method for the isolation of 3x FLAG-tagged proteins from the membrane and soluble fractions of Synechocystis. Soluble proteins or solubilized thylakoids are subjected to a single affinity purification step that utilizes the highly specific binding of FLAG-affinity resin. After an intensive wash, the captured proteins are released from the resin under native conditions using an excess of synthetic 3x FLAG peptide. The protocol allows fast isolation of low abundant protein complexes with a superb purity.

Isolation and Characterization of Exosomes from Mouse Feces

CY Chunhua Yang

MZ Mingzhen Zhang

JS Junsik Sung

LW Lixin Wang

YJ Yunjin Jung

DM Didier Merlin

0 Q&A

7718 Views

Apr 20, 2020

Exosomes secreted by colonic epithelial cells are present in feces and contain valuable epigenetic information, such as miRNAs, proteins, and metabolites. An in-depth study of this information is conducive to the diagnosis or treatment of relevant diseases. A crucial prerequisite of such a study is to establish an efficient isolation method, through which we can obtain a relatively more significant amount of exosomes from feces. This protocol is designed to effectively isolate a large number of exosomes from contaminants and other particles in feces by a combined method with fast filtration and sucrose density gradient ultracentrifugation. Exosomes generated by this method are suitable for further RNA, protein, and lipid analysis.

Production, Purification and Characterization of Recombinant Biotinylated Phytochrome B for Extracellular Optogenetics

MH Maximilian Hörner

OY O. Sascha Yousefi

WS Wolfgang W. A. Schamel

WW Wilfried Weber

0 Q&A

5869 Views

Mar 5, 2020

In the field of extracellular optogenetics, photoreceptors are applied outside of cells to obtain systems with a desired functionality. Among the diverse applied photoreceptors, phytochromes are the only ones that can be actively and reversibly switched between the active and inactive photostate by the illumination with cell-compatible red and far-red light. In this protocol, we describe the production of a biotinylated variant of the photosensory domain of A. thaliana phytochrome B (PhyB-AviTag) in E. coli with a single, optimized expression plasmid. We give detailed instructions for the purification of the protein by immobilized metal affinity chromatography and the characterization of the protein in terms of purity, biotinylation, spectral photoswitching and the light-dependent interaction with its interaction partner PIF6. In comparison to previous studies applying PhyB-AviTag, the optimized expression plasmid used in this protocol simplifies the production process and shows an increased yield and purity.

A Refined Protocol for Identifying Citrulline-specific Monoclonal Antibodies from Single Human B Cells from Rheumatoid Arthritis Patient Material

kA Khaled Amara

LI Lena Israelsson

RS Ragnhild Stålesen

PS Peter Sahlström

JS Johanna Steen

VM Vivianne Malmström

CG Caroline Grönwall

0 Q&A

7034 Views

Sep 5, 2019

We describe here a detailed, refined protocol for the generation of citrulline-specific monoclonal antibodies from single human B cells from rheumatoid arthritis (RA) patients. This protocol provides a detailed guide of the procedure starting from single B cells of your choice and followed by amplification of the variable region of immunoglobulin genes by RT-PCR, subsequent immunoglobulin gene cloning, recombinant IgG1 monoclonal antibody (mAb) production and quality controls. The produced mAbs can be used for further studies including reactivity towards candidate antigens and functionality both in vitro and in vivo. This protocol can be used to generate antigen-specific mAbs from B cells derived from different tissues and compartments, including peripheral blood, synovial fluid, digested biopsies, bone marrow aspirations, and bronchoalveolar lavage fluid. Notably, although examples are given on how to identify citrulline-specific autoantibodies the general methods can also be applied to other reactivities.

Deoxycholate Fractionation of Fibronectin (FN) and Biotinylation Assay to Measure Recycled FN Fibrils in Epithelial Cells

Archana Varadaraj

Carina Magdaleno

KM Karthikeyan Mythreye

0 Q&A

6870 Views

Aug 20, 2018

Fibronectin (FN) is an extracellular matrix protein that is secreted by many cell types and binds predominantly to the cell surface receptor Integrin α5β1. Integrin α5β1 binding initiates the step-wise assembly of FN into fibrils, a process called fibrillogenesis. We and several others have demonstrated critical effects of fibrillogenesis on cell migration and metastasis. While immunostaining and microscopy methods help visualize FN incorporation into fibrils, with each fibril being at least 3 μm in length, the first study that developed a method to biochemically fractionate FN to quantify fibril incorporated FN was published by Jean Schwarzbauer’s group in 1996. Our protocol was adapted from the original publication, and has been tested on multiple cell types including as shown here in MCF10A mammary epithelial and Caki-1 renal cancer epithelial cells. Using two detergent extractions, cellular FN is separated into detergent insoluble or fibril incorporated FN and soluble FN or unincorporated fractions. To determine whether fibrillogenesis utilizes a recycled pool of FN, we have used a Biotin labeled FN (FN-Biotin) recycling assay, that has been modified from a previous study. Using a combination of the recycling assay and deoxycholate fractionation methods, one can quantitatively demonstrate the extent of fibrillogenesis in cells under different experimental conditions and determine the source of FN for fibrillogenesis.

Mammalian Cell-derived Vesicles for the Isolation of Organelle Specific Transmembrane Proteins to Conduct Single Molecule Studies

FM Faruk H. Moonschi

AF Ashley M. Fox-Loe

XF Xu Fu

CR Chris I. Richards

0 Q&A

7589 Views

May 5, 2018

Cell-derived vesicles facilitate the isolation of transmembrane proteins in their physiological membrane maintaining their structural and functional integrity. These vesicles can be generated from different cellular organelles producing, housing, or transporting the proteins. Combined with single-molecule imaging, isolated organelle specific vesicles can be employed to study the trafficking and assembly of the embedded proteins. Here we present a method for organelle specific single molecule imaging via isolation of ER and plasma membrane vesicles from HEK293T cells by employing OptiPrep gradients and nitrogen cavitation. The isolation was validated through Western blotting, and the isolated vesicles were used to perform single molecule studies of oligomeric receptor assembly.

Fish Bile Clean-up for Subsequent Zymography and Mass Spectrometry Proteomic Analyses

Rachel Ann Hauser-Davis

0 Q&A

8037 Views

Jan 20, 2018

Biliary excretion offers a way to analyze various contaminants in aquatic organisms, and fish bile has been used as a biomarker for environmental contamination. The use of the fish bile proteome as a tool for monitoring the impact of environmental contaminants has been recently validated. However, scarce studies in this context are available, and much remains to be investigated. In this context, this protocol describes a fast, reproducible and cheap biliary clean-up procedure for subsequent proteomic analyses, such as zymography and mass spectrometry.

Extraction of Soluble and Insoluble Protein Fractions from Mouse Brains and Spinal Cords

Oliver Wirths

3 Q&A

29393 Views

Aug 5, 2017

The current protocol details the preparation of soluble and insoluble protein lysates from mouse brain or spinal cord samples. In detail, tissue homogenization and sequential protein extraction are described. This procedure yields soluble and insoluble protein extracts that can be further processed in down-stream applications like ELISA or Western blotting.