LocusLink

Introduction:

LocusLink (http://www.ncbi.nlm.nih.gov/LocusLink) is a National Center for Biotechnology

Information (NCBI) online resource. It is principally intended for use by graduate students and

professional researchers in the biomedical sciences. It is designed to bring together related information

on genetic loci and gene products from several sources. LocusLink provides a central point of access for

basic biomedical information and molecular data for genes, transcripts, and proteins from model

organisms, currently including human, rat, mouse, fruit fly, and zebrafish.

LocusLink relate to PubMed, RefSeq, and other NCBI databases

NCBI has a large and growing number of search tools for biologists to obtain information. A few

of these include:

PubMed: a searchable biomedical literature citation index. For a given genetic locus, LocusLink

leads directly to a short list of PubMed citations for that gene. (This list usually includes reports

pertaining to central genetic or molecular biological discoveries, and to reports on disease-causing alleles,

for the gene in question.)

RefSeq: Another new NCBI database, RefSeq (Reference Sequence) entries are intended to serve

as "authority files" for genetic sequence information. For a given genetic open reading frame, RefSeq

provides a curated file on the gene sequence and its transcriptional and translational processing (where

available). An professional review process helps to ensure the biological accuracy of these authority

files. RefSeq files are accessible directly from the LocusLink entry for the genetic locus in question.

OMIM (Online Mendelian Inheritance in Man): a database of human genes and genetic diseases,

including knowledge of their molecular and physiological roles and causes. The writeups for genetic loci

and their roles in physiology are often extensive and are frequently updated. OMIM files are accessible

directly from the LocusLink entry for the genetic locus in question.

GenBank, Protein Database, Homologene, UniGene, genetic variations database (single

nucleotide polymorphisms): links to gene-specific information from each of these databases are directly

available from the LocusLink entry for the genetic locus in question.

Steps involved in the usage of LocusLink

Go to the LocusLink home page: http://www.ncbi.nlm.nih.gov/LocusLink.

Although an alphabetical list of entries is available, LocusLink can be most easily searched using

the query box at the top of the page.

Users can enter a wide variety of terms, for example: gene name or gene symbol (e.g., SDHA),

protein name (succinate dehydrogenase flavoprotein), protein symbol (SDH), EC (Enzyme

Commission) number (1.3.5.1), and disease states (Leigh syndrome).

Type in your search query into the "Query:" box, then press "go".

If multiple terms are entered (e.g., succinate dehydrogenase) the search engine automatically

searched for files containing both words (succinate and dehydrogenase) in the file. Searches can

also be constructed using the terms AND, OR (to find files containing both or either search

terms), and NOT (to find files containing the first but not the second term).

On the results page, first note that the number of entries returned is given. If you get no results,

refer to the "help" section, linked in the left-hand bar on the page.

"Description" is a brief explanation of the function of the locus.

The "Position" column gives the chromosomal map location of the genetic locus. Clicking the

blue entry links to a visual chromosomal map with the gene marked on it.

The rainbow-colored "Links" column gives links to several other NCBI databases:

“P” PubMed

“O” Online Mendelian Inheritance in Man (OMIM)

“R” RefSeq database

“G” GenBank database

“P” Protein database

“H” Homologene database

“U” Unigene database

“V” Variation data: single nucelotide polymorphism (SNP) database