SP-C is a fragment of a much larger precursor protein of 21 kD. The precursor contains an exceedingly hydrophobic region of 34 amino acids that comprises most of the mature SP C, and a unique poly-valine domain.Pulmonary surfactant-associated protein C is a membrane protein which manufactures surfactant.Humans and animals born lacking SP-C tend to develop progressive interstitial pneumonitis.The SFTPC gene encodes pulmonary-associated surfactant protein C (SPC), an extremely hydrophobic surfactant protein essential for lung function and homeostasis after birth. It is produced exclusively by type II alveolar epithelial cells in the lung. Pulmonary surfactant is a lipid-rich material that prevents lung collapse by lowering surface tension at the air-liquid interface in the alveoli of lung.