Difference between DNA and Protein Microarray

Microarray

A microarray is a laboratory tool used to detect the expression of thousands of genes at once. It is a lab on chip method. It is a hybridization technique usually performed on two dimensional solid substrates, such as glass slides or silicon thin-film cells. These slides are often called gene chips.

The target samples are hybridized with a large set of oligonucleotide probes, attached to the solid support. It tells us the sequence of the samples or any gene variation in the sequence or used for gene mapping.

It was first illustrated by Tse Wen Chang in 1983 for antibody microarray.

DNA and Protein Microarray are two of the many types of microarray technology.

DNA Microarray

A DNA microarray is more commonly known as a DNA chip or biochip. DNA spots in picomoles (10-12) are attached to a solid surface, that is known as probes. Both the sample DNA and target DNA are either attached to fluorophore or chemiluminescence labelled and then allowed to hybridize.

For example, mRNA from a healthy and diseased individual is collected for the detection of disease. Both the mRNAs are converted to cDNA and labelled with green and red fluorescent dyes, respectively. The two samples are then allowed to hybridize together.

If the expression of healthy mRNA is more, a green dot is seen on the slide. Similarly, a red dot is seen for higher expression of the diseased mRNA. Finally, a yellow dot appears on the slide when both the mRNAs are expressed equally.

The DNA chip can be studied this way for gene profiling, SNP detection, comparative genomic hybridization, etc.

Protein Microarray

Protein microarray, more commonly known as protein chip, is a high throughput technique used to track the activities, functions and interactions of proteins. The main advantage lies in the fact that a large number of proteins can be tracked at once.

Similar to DNA chips the probe proteins are fluorescently labelled and allowed to hybridize with the target proteins, the light emitted is read by a laser scanner. The solid surface used in protein microarray is glass slides, nitrocellulose membrane, bead or microtitre plates.

The technique is automated, rapid, sensitive, economical, and requires small quantities of proteins and probes.

DNA vs Protein Microarray

DNA Microarray
Protein Microarray
Definition
DNA microarray is an arrangement of DNA spots (in picomole) attached to a solid surface. A protein microarray is a collection of purified proteins on a solid surface.
Labelling
Either probe or target DNA is labelled or both are labelled. Only probes are labelled.
Solid surfaces
Glass slide or silicon thin-film cells. Glass slide, nitrocellulose membrane, bead and microtitre plates.
Application
Used in gene expression profiling, chromatin immunoprecipitation, SNP detection, comparative genomic hybridization, etc. It is used in proteomics, diagnostics, protein functional analysis, treatment development and antibody characterization.

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Frequently Asked Questions

What are the different types of protein microarrays?

The three types of protein microarrays are analytical microarrays, functional microarrays and reverse phase microarrays.

Is ELISA a protein microarray?

Yes, ELISA is a protein microarray used to quantify proteins in biological samples.

How many types of microarrays are there?

Different types of microarray are DNA microarrays, protein microarrays, peptide microarrays and antibody microarrays.

Who invented the DNA microarray?

DNA microarray was invented by Patrick O. Brown.

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