Since the dentine is analogous to bone, its extracellular matrix shares many similarities to bone tissues. Similar to the bone, type I collagen is the major organic component in dentine. However, little is known about minor fibrillar collagens, which seem to be co-expressed such as type I or II collagen. The present study examined the gene expression of type V and XI collagens, which play important roles in collagen fibril formation and skeletal morphogenesis, using RT-PCR and in situ hybridization combined with immunohistochemistry. The transcripts of pro-alpha 1(XI), pro-alpha 2(XI), pro-alpha 1(V) and pro-alpha 2(V) chains were present, but not pro-alpha 3(V) and pro-alpha 1(II) chains, of which an overglycosylated variant is pro-alpha 3(XI) chain, in mouse incisor tooth, using RT-PCR and in situ hybridization. The pro-alpha 2(XI) protein, which is mainly expressed in cartilage, were observed in the odontoblast using a specific polyclonal antibody. Real-time RT-PCR showed that the transcripts of pro-alpha 2(XI), pro-alpha 1(V) and pro-alpha 2(V) were predominant in crown and that of pro-alpha 1(XI) in root of the tooth. Finally, the expression of pro-alpha 2(XI) was confirmed with an odontoblastic cell line transformed with human telomerase reverse transcriptase (hTERT) both in vitro and in vivo. The data suggest a new subtype of the V/XI collagen molecule containing alpha 2(XI) chain. (C) 2010 Elsevier Inc. All rights reserved.