The RefSeq Genes track shows known protein coding genes taken from mRNA reference sequences compiled at LocusLink. Coding exons are represented by blocks connected by horizontal lines representing introns. The 5' and 3' untranslated regions (UTRs) are displayed as shorter blocks on the leading and trailing ends of the aligning regions. In full display mode, arrowheads on the connecting intron lines indicate the direction of transcription.
Non-coding RNA genes have their own track in some assemblies.
Refseq mRNAs are aligned against the genome using the blat program. When a single mRNA aligns in multiple places, only the best alignments that also have at least 98% sequence identity are kept.
The RefSeq Genes track is produced at UCSC from mRNA sequence data generated by scientists worldwide and curated by the NCBI RefSeq project.