LCM isolates specific cells or tissues from samples mounted on microscope slides. The samples are viewed through a thermoplastic film that is attached to a microcentrifuge tube lid. Localized heat, caused by the application of a laser pulse, fuses the membrane to the cells of interest, which can then be harvested for further analysis. RNA and proteins can be purified from the isolated cells, allowing detailed analysis of gene expression. This protocol is divided into three stages. - [Read (LCM): Preparation and Sectioning of Frozen Tissue Blocks and Purification of RNA from Isolated Cel]
This assay is performed to detect ubiquitylated proteins in yeast. Yeast that have been transformed with a vector expressing polyhistidine-tagged ubiquitin (Ub) under the control of a copper-inducible promoter are grown, induced with copper, and harvested. Total ubiquitylated proteins are then recovered by nickel-affinity chromatography, and specific proteins are detected by Western blotting. - [Read Detection of Ubiquitylated Proteins in Yeast Protocol]
Coimmunoprecipitation is most commonly used to test whether two proteins of interest are associated in vivo, but it can also be used to identify novel interacting partners of a target protein. In both cases, the cells, which may have been labeled with [35S]methionine, are harvested and lysed under conditions that preserve protein-protein interactions. The target protein is specifically immunoprecipitated from the cell extracts, and the immunoprecipitates are fractionated by SDS-PAGE. - [Read Identification of Associated Proteins by Coimmunoprecipitation Protocol]
In this protocol nuclei isolated from cells expressing the gene of interest are incubated with radiolabeled UTP which is incorporated into nascent RNA transcripts by RNA polymerase molecules that were actively transcribing at the time the cells were harvested. Because very little denovo initiation of RNA synthesis occurs in isolated nuclei, transcription of the target gene can be measured by hybridizing the radiolabeled RNA to an excess of the target gene immobilized on a nitrocellulose or nylon - [Read Protocol for Transcriptional Run- On Assays]