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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
The collagen triple helix structure is not found in -
assistant
The correct answer is  Triple helix formation occurs in endoplasmic reticulum at procollagen level.
Triple helix of procollagen is packed into secretory intracellular vesicles in the Golgi-apparatus.
These vesicles then secrete the procollagen into extracellular space where it is converted to tropocollagen (collagen monomer).
Tropocollagens aggregate into collagen fibrils which intern become extensively cross-linked to form 'collagen fibers'.