Tips on Finding cDNA Clones
Many Clones Are Available
To accelerate the pace of biomedical research, tens of thousands of
cDNA and expression clones have been assembled into collections that are
readily available to the scientific community. Before setting out to
construct and characterize a new clone, it is worth a few minutes at the
computer to see if one already exists.
Finding Clones for a Gene
When searching the NCBI Gene Database, look for "NIH cDNA clone"
hypertext links, which lead to one or more cDNA sequences. Similar links
may be found on protein and UniGene entries.
In the full report for a gene, look in the "Links" section on the
right for possible MGC clones.
Searching for Clone Sequences
In addition to finding cDNA clone sequences by following links from
the Gene report, the Nucleotide sequence database may be searched directly.
When doing this, it is useful to include "MGC" qualified as a keyword to
limit the results to sequences of clones from the MGC collection. For
convenience, clones from the ZGC and XGC collections also have "MGC" as
a keyword. Try the following sample queries.
MGC[Keyword] AND apoptosis
Clone Sequence Entries
After finding a cDNA sequence of interest, examine the COMMENTS section
for general information on availability.
Clone identifiers and other specific
information are in the FEATURES section under "source".
Clone distributors are encouraged to use the NCBI's LinkOut system to
provide links to online order forms or other information. LinkOut is a
generic mechanism for attaching links to any NCBI database object, such
as a gene or a sequence. To see if LinkOut information exists, click on
the word "Links" (see graphic) and look for LinkOut on the drop-down menu.
In this example, three of the cDNA clone distributors (Geneservice Ltd., Open Biosystems, and RZPD)
have provided links to their sites for online ordering. Links for other types of
reagents (such as probes and primers) may also be present.
Mammalian Gene Collection
The NIH Mammalian Gene Collection (MGC) project aims to identify at least one full-ORF cDNA
clone for each human and mouse gene, produce a high-accuracy sequence, and make the physical
reagents easily available to researchers. The collection is augmented by a limited number of
rat cDNAs and non-mammalian clones coming from the affiliated Zebrafish (ZGC) and
Xenopus (XGC) projects.
What Is LinkOut?
LinkOut is a feature of the NCBI Entrez system that allows links to any web
resource to be attached to any database entry. This allows users to find relevant
biological materials, research tools, full-text publications, consumer health
information, and more.
General LinkOut Information
Information for LinkOut Providers