Complex sentence: Collagen, type I, alpha 1, also known as COL1A1, is a human gene that encodes the major component of type I collagen, the fibrillar collagen found in most connective tissues, including cartilage.
Split into simpler sentences: Collagen, type I, alpha 1, also known as alpha-1 type I collagen, is a protein that in humans is encoded by the "COL1A1" gene. COL1A1 encodes the major component of type I collagen, the fibrillar collagen found in most connective tissues, including cartilage.