| Functional |
"MMP20 diverged from other matrix metalloproteinase loci prior to the common ancestry of tetrapods [24], and plays a key role in processing structural proteins (amelogenin, ameloblastin, enamelin) that are secreted into the extracellular matrix by ameloblasts during the secretory stage of enamel formation [23,25–28]." |
10.1098/rspb.2010.1280 |
| Mutation Description |
"Representative mysticete sequences from exons 3 and 4 of MMP20 lack frameshift mutations and stop codons, but we discovered a CHR-2 SINE insertion in exon 2 that is shared by eight mysticete species that are representative of all extant mysticete genera." |
10.1098/rspb.2010.1280 |
| Mutation Description |
"Within Mysticeti, a 1 bp insertion at position 552 is present in the pygmy right whale, Caperea marginata, and a G to T point mutation at position 532 in the common minke whale, Balaenoptera acutorostrata, results in an ochre (‘TAA’) stop codon (electronic supplementary material, alignment 1)." |
10.1098/rspb.2010.1280 |
| Timing of Loss |
"The SINE insertion in exon 2 of MMP20 provides the first molecular evidence for pseudogenization of the genetic toolkit for enamel production in the common ancestor of extant mysticetes (figure 2)." |
10.1098/rspb.2010.1280 |
| Phenotypic |
"Given that MMP20 is required for proper processing of amelogenin, ameloblastin and enamelin, and may also be required for KLK4 activation; this insert provides compelling evidence that normal enamel formation was abrogated no later than the date of this SINE insertion." |
10.1098/rspb.2010.1280 |