Term child term update: Remove Collagen type XIX trimer (GO:1990318) from FACIT collagen trimer (GO:0005593)

[DaiqingChen]

• GO term ID and label for which you request a definition update
  Collagen type XIX trimer (GO:1990318), FACIT collagen trimer (GO:0005593)

• New proposed definition (genus-differentia pattern, plus additional information if needed)
  A collagen homotrimer made of three alpha1(XIX) collagen chains, each presenting interrupted triple helical collagen domains; localizes to basement membrane ECMs, not known to associate with any fibrillar collagens that are predominantly found in the interstitial extracellular matrix.

• Reference(s)
  PMID: 31823868; PMID: 9403723; PMID: 35346795; PMID: 12788917; PMID: 10585282; PMID: 12579531 provided by Dr. Sylvie Ricard-Blum.

• Additional information
  The collagen XIX trimer is often classified as a FACIT collagen trimer because of the presence of interrupted triple helical collagen domains, similar to other FACIT members. However, evidence show that collagen XIX localizes to basement membrane ECMs, and none of the basement membrane collagens are fibrillar. As such, we propose to remove collagen XIX from the FACIT (which stands for Fibril Associated Collagens with Interrupted Triple helices) classification and to position it directly under the "Collagenous component of basement membrane" CC (Add term Collagenous component of basement membrane #29472).