Type IV collagen synthesis by cultured mouse keratinocytes (Pam cells)

The collagens synthesized by Pam cells were biochemically characterized. The collagen in the cell layers was identified as type IV collagen by immunoprecipitation with type IV collagen specific antibody. The apparent molecular weights were 180 Kd and 175 Kd, which converted to major (160 Kd) and several minor smaller fragments with pepsin treatment. The ratios of 3-hydroxyproline/4-hydroxyproline and 4-hydroxyproline/proline in the 160 Kd polypeptide were 0.11 and 1.18, respectively. The result shows that Pam cells are able to produce type IV collagen whose biochemical characteristics are similar to those from other epithelial cells. In the kinetic study, the synthesis of type IV collagen reached its maximum level rapidly on the 1st day after seeding, suggesting that type IV collagen may play a role in cell attachment and proliferation.