N-telopeptide crosslinks and bone collagen

Pyridinoline crosslinks occur in many types of collagen outside of bone. One type of pyridinoline crosslink that is more common in bone collagen is the pyridinoline crosslink in the N-telopeptide region (NTX). These crosslinks joins alpha-1 molecules to alpha-2 molecules (lower right) in bone collagen; in other tissues, these crosslinks join alpha-1 to alpha-1 molecules (upper left).