Model illustrating the involvement of SLRPs in the regulation of linear and lateral fibril growth. Collagen fibrillogenesis is a multiple-step process that is tightly regulated by the interaction of various molecules. The initial step involves heterotypic collagen I/V nucleation at the cell surface, then SLRPs bind to the protofibril surface, regulating the linear growth and lateral growth of protofibrils to mature collagen fibrils. Deficiency of SLRPs leads to dysfunctional linear and lateral fusion, with alterations in fibril structure and function.¹⁶