Toeprinting assay

Last updated

The toeprinting assay, also known as the primer extension inhibition assay, [1] is a method used in molecular biology that allows one to examine the interactions between messenger RNA and ribosomes or RNA-binding proteins. [2] It is different from the more commonly used DNA footprinting assay. The toeprinting assay has been utilized to examine the formation of the translation initiation complex. [3]

To do a toeprint assay, one needs the mRNA of interest, ribosomes, a DNA primer, free nucleotides, and reverse transcriptase (RT), among other reagents. [4] The assay involves letting the RT generate cDNA until it gets blocked by any bound ribosomes, resulting in shorter fragments called toeprints when the results are observed on a sequencing gel.

Related Research Articles

<span class="mw-page-title-main">Locked nucleic acid</span> Biological molecule

A locked nucleic acid (LNA), also known as bridged nucleic acid (BNA), and often referred to as inaccessible RNA, is a modified RNA nucleotide in which the ribose moiety is modified with an extra bridge connecting the 2' oxygen and 4' carbon. The bridge "locks" the ribose in the 3'-endo (North) conformation, which is often found in the A-form duplexes. This structure provides for increased stability against enzymatic degradation. LNA also offers improved specificity and affinity in base-pairing as a monomer or a constituent of an oligonucleotide. LNA nucleotides can be mixed with DNA or RNA residues in a oligonucleotide.

The Pribnow box is a sequence of TATAAT of six nucleotides that is an essential part of a promoter site on DNA for transcription to occur in bacteria. It is an idealized or consensus sequence—that is, it shows the most frequently occurring base at each position in many promoters analyzed; individual promoters often vary from the consensus at one or more positions. It is also commonly called the -10 sequence or element, because it is centered roughly ten base pairs upstream from the site of initiation of transcription.

<span class="mw-page-title-main">Morpholino</span> Chemical compound

A Morpholino, also known as a Morpholino oligomer and as a phosphorodiamidate Morpholino oligomer (PMO), is a type of oligomer molecule used in molecular biology to modify gene expression. Its molecular structure contains DNA bases attached to a backbone of methylenemorpholine rings linked through phosphorodiamidate groups. Morpholinos block access of other molecules to small specific sequences of the base-pairing surfaces of ribonucleic acid (RNA). Morpholinos are used as research tools for reverse genetics by knocking down gene function.

<span class="mw-page-title-main">Mature messenger RNA</span> Eukaryotic RNA transcript

Mature messenger RNA, often abbreviated as mature mRNA is a eukaryotic RNA transcript that has been spliced and processed and is ready for translation in the course of protein synthesis. Unlike the eukaryotic RNA immediately after transcription known as precursor messenger RNA, mature mRNA consists exclusively of exons and has all introns removed.

<span class="mw-page-title-main">Nucleoprotein</span> Type of protein

Nucleoproteins are proteins conjugated with nucleic acids. Typical nucleoproteins include ribosomes, nucleosomes and viral nucleocapsid proteins.

An internal ribosome entry site, abbreviated IRES, is an RNA element that allows for translation initiation in a cap-independent manner, as part of the greater process of protein synthesis. In eukaryotic translation, initiation typically occurs at the 5' end of mRNA molecules, since 5' cap recognition is required for the assembly of the initiation complex. The location for IRES elements is often in the 5'UTR, but can also occur elsewhere in mRNAs.

Bacterial translation is the process by which messenger RNA is translated into proteins in bacteria.

<span class="mw-page-title-main">Real-time polymerase chain reaction</span> Laboratory technique of molecular biology

A real-time polymerase chain reaction is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, not at its end, as in conventional PCR. Real-time PCR can be used quantitatively and semi-quantitatively.

<span class="mw-page-title-main">Electrophoretic mobility shift assay</span>

An electrophoretic mobility shift assay (EMSA) or mobility shift electrophoresis, also referred as a gel shift assay, gel mobility shift assay, band shift assay, or gel retardation assay, is a common affinity electrophoresis technique used to study protein–DNA or protein–RNA interactions. This procedure can determine if a protein or mixture of proteins is capable of binding to a given DNA or RNA sequence, and can sometimes indicate if more than one protein molecule is involved in the binding complex. Gel shift assays are often performed in vitro concurrently with DNase footprinting, primer extension, and promoter-probe experiments when studying transcription initiation, DNA gang replication, DNA repair or RNA processing and maturation, as well as pre-mRNA splicing. Although precursors can be found in earlier literature, most current assays are based on methods described by Garner and Revzin and Fried and Crothers.

The Kozak consensus sequence is a nucleic acid motif that functions as the protein translation initiation site in most eukaryotic mRNA transcripts. Regarded as the optimum sequence for initiating translation in eukaryotes, the sequence is an integral aspect of protein regulation and overall cellular health as well as having implications in human disease. It ensures that a protein is correctly translated from the genetic message, mediating ribosome assembly and translation initiation. A wrong start site can result in non-functional proteins. As it has become more studied, expansions of the nucleotide sequence, bases of importance, and notable exceptions have arisen. The sequence was named after the scientist who discovered it, Marilyn Kozak. Kozak discovered the sequence through a detailed analysis of DNA genomic sequences.

A ribosome binding site, or ribosomal binding site (RBS), is a sequence of nucleotides upstream of the start codon of an mRNA transcript that is responsible for the recruitment of a ribosome during the initiation of translation. Mostly, RBS refers to bacterial sequences, although internal ribosome entry sites (IRES) have been described in mRNAs of eukaryotic cells or viruses that infect eukaryotes. Ribosome recruitment in eukaryotes is generally mediated by the 5' cap present on eukaryotic mRNAs.

<span class="mw-page-title-main">Untranslated region</span> Non-coding regions on either end of mRNA

In molecular genetics, an untranslated region refers to either of two sections, one on each side of a coding sequence on a strand of mRNA. If it is found on the 5' side, it is called the 5' UTR, or if it is found on the 3' side, it is called the 3' UTR. mRNA is RNA that carries information from DNA to the ribosome, the site of protein synthesis (translation) within a cell. The mRNA is initially transcribed from the corresponding DNA sequence and then translated into protein. However, several regions of the mRNA are usually not translated into protein, including the 5' and 3' UTRs.

<span class="mw-page-title-main">EF-G</span> Prokaryotic elongation factor

EF-G is a prokaryotic elongation factor involved in protein translation. As a GTPase, EF-G catalyzes the movement (translocation) of transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome.

<span class="mw-page-title-main">28S ribosomal RNA</span> RNA component of the large subunit of the eukaryotic ribosome

28S ribosomal RNA is the structural ribosomal RNA (rRNA) for the large subunit (LSU) of eukaryotic cytoplasmic ribosomes, and thus one of the basic components of all eukaryotic cells. It has a size of 25S in plants and 28S in mammals, hence the alias of 25S–28S rRNA.

Periannan Senapathy is a molecular biologist, geneticist, author and entrepreneur. He is the founder, president and chief scientific officer at Genome International Corporation, a biotechnology, bioinformatics, and information technology firm based in Madison, Wisconsin, which develops computational genomics applications of next-generation DNA sequencing (NGS) and clinical decision support systems for analyzing patient genome data that aids in diagnosis and treatment of diseases.

<span class="mw-page-title-main">Reverse Transcription Loop-mediated Isothermal Amplification</span>

Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is a one step nucleic acid amplification method to multiply specific sequences of RNA. It is used to diagnose infectious disease caused by RNA viruses.

Monica Riley was an American scientist who contributed to the discovery of messenger RNA in her Ph.D work with Arthur Pardee, and was later a pioneer in the exploration and computer representation of the Escherichia coli genome.

Marilyn S. Kozak is an American professor of biochemistry at the Robert Wood Johnson Medical School. She was previously at the University of Medicine and Dentistry of New Jersey before the school was merged. She was awarded a PhD in microbiology by Johns Hopkins University studying the synthesis of the Bacteriophage MS2, advised by Daniel Nathans. In her original faculty job proposal, she sought to study the mechanism of eukaryotic translation initiation, a problem long thought to have already been solved by Joan Steitz. While in the Department of Biological Sciences at University of Pittsburgh, she published a series of studies that established the scanning model of translation initiation and the Kozak consensus sequence. Her current research interests are unknown as her last publication was in 2008.

The ViennaRNA Package is a set of standalone programs and libraries used for prediction and analysis of RNA secondary structures. The source code for the package is distributed freely and compiled binaries are available for Linux, macOS and Windows platforms. The original paper has been cited over 2000 times.

Donna R. Maglott is a staff scientist at the National Center for Biotechnology Information known for her research on large-scale genomics projects, including the mouse genome and development of databases required for genomics research.


  1. Hartz, D.; McPheeters, D. S.; Traut, R.; Gold, L. (1988-01-01). Extension inhibition analysis of translation initiation complexes. Methods in Enzymology. Vol. 164. pp. 419–425. doi:10.1016/s0076-6879(88)64058-4. ISSN   0076-6879. PMID   2468068.
  2. Shirokikh, Nikolay E.; Alkalaeva, Elena Z.; Vassilenko, Konstantin S.; Afonina, Zhanna A.; Alekhina, Olga M.; Kisselev, Lev L.; Spirin, Alexander S. (2010-01-01). "Quantitative analysis of ribosome–mRNA complexes at different translation stages". Nucleic Acids Research. 38 (3): e15. doi:10.1093/nar/gkp1025. ISSN   0305-1048. PMC   2817456 . PMID   19910372.
  3. Chang, J T; Green, C B; Wolf, R E (1995-11-01). "Inhibition of translation initiation on Escherichia coli gnd mRNA by formation of a long-range secondary structure involving the ribosome binding site and the internal complementary sequence". Journal of Bacteriology. 177 (22): 6560–6567. doi:10.1128/jb.177.22.6560-6567.1995. ISSN   0021-9193. PMC   177509 . PMID   7592434.
  4. Kozak, M (1998-11-01). "Primer extension analysis of eukaryotic ribosome-mRNA complexes". Nucleic Acids Research. 26 (21): 4853–4859. doi:10.1093/nar/26.21.4853. ISSN   0305-1048. PMC   147915 . PMID   9776744.