Models of the human primosome during key steps of RNA primer synthesis.
A, at the initiation step, p58C fits into a space between p180core and p49. B, at the RNA elongation step, p58C is moving toward p180core and displaces it from the p49-p58N-p180C-p70 platform. C, flexibly tethered p180core binds DNA template with a 9-mer RNA primer presented by p58C.