Partial characterization of an unusual 185 kDa protein synthesized by dermal fibroblasts from patients with Marfan syndrome: identification of the protein as type IV collagen.

Production of an unusual collagenous protein was observed in culture of dermal fibroblasts from four patients with Marfan syndrome. The apparent molecular weight of the protein was about 185 kDa after reduction with 2-mercaptoethanol and 175 kDa after limited pepsin treatment. The 185 kDa protein was susceptible to the bacterial collagenase but resistant to the animal collagenase. Immunoprecipitation revealed the specific interaction of the pepsin-treated 175 kDa collagenous protein with monoclonal and polyclonal antibodies to human type IV collagen. From the patterns of CNBr peptide mapping the 185 kDa band was identified as alpha 1 (IV) chain. Type IV collagen in the skin is generally considered to be of non-fibroblastic origin. However, in "diseased" condition, dermal fibroblasts might produce type IV collagen. The clinical manifestation in relation to production of type IV collagen by cultured skin fibroblasts from Marfan patients is discussed.