MatK

matK is a chloroplast gene that encodes maturase K, a protein involved in the splicing of group II introns in chloroplast transcripts. In most land plants, matK lies within the large intron of the trnK-UUU gene, and its coding sequence is typically about 1,400 to 1,500 base pairs long, translating to roughly 450–500 amino acids. The matK maturase is considered a degenerate, domain-reduced form of a typical group II intron maturase, and while it retains a role in intron splicing, it is not thought to be fully autonomous in intron mobility.

Functionally, matK is primarily associated with the maturation of chloroplast RNA transcripts. It is believed to facilitate splicing of several chloroplast group II introns, contributing to the proper expression of essential photosynthesis-related and other chloroplast genes. Its exact biochemical mechanisms are still studied, but matK is recognized as a chloroplast-encoded maturase that has diverged from classical, fully featured maturases found in other contexts.

In DNA barcoding and plant phylogenetics, matK is valued for its relatively high rate of sequence evolution among coding chloroplast genes, which provides good discrimination at the species level for many groups of plants. It is frequently used in combination with the rbcL gene to improve taxa identification and phylogenetic resolution. While matK often yields informative data, primer universality can vary among taxa, and alignment can be challenging in highly divergent lineages or when sequences contain insertions or deletions. Despite these caveats, matK remains one of the most widely sequenced chloroplast genes for plants and a standard reference in phylogenetic studies.