Involved in cell-matrix and cell-cell adhesion interactions that are required for normal development. May participate in the linkage between muscle fiber and basement membrane. May play a role in endochondral ossification of bone and branching morphogenesis of lung. Binds heparin. At neuromuscular junctions, may play a role in acetylcholine receptor clustering (PubMed:26626625). Homotrimer; disulfide-linked. Nucleation of the type XIII collagen triple helix is likely to occur at the N-terminal region with triple helix formation proceeding from the N- to the C-terminus. Interacts with FN1, perlecan/HSPG2 and NID2 (By similarity). Additional isoforms may exist. Expression levels remain fairly constant during early fetal development. This is followed by a marked increase of expression levels during the final stages of organogenesis, with initiation of the rapid fetal growth phase before birth. At mid-gestation, strongly expressed in the central and peripheral nervous systems. Also strongly expressed in developing heart, with localization to cell-cell contacts and accentuated in intercalated disks perinatally. During late fetal development, expressed in many tissues including cartilage, bone, skeletal muscle, lung, intestine and skin. Not detected in endothelia of most blood vessels or the endocardium of the heart. Transgenic mice overexpressing COL13A1 with a 90 amino acid in-frame deletion of the COL2 sequence show embryonic lethality due either to a lack of placental formation or to cardiovascular defects in offspring from heterozygous mating. In contrast, transgenic mice expressing an N-terminally altered COL13A1 lacking both cytosolic and transmembrane domains while retaining the collagenous ectodomain are viable and fertile, but display progressive muscular myopathy.