Dynal Biotech's Dynabeads and Dynabeads MyOne are examples of magnetic micro-particle technology that provides a cleaner and easier to use support level for protein handling, including immobilization for downstream analyses. When the correct bead and chemistry are carefully selected, complex procedures can be performed that depend on the solid phase nature of the beads, and very strict interactions can be used to isolate and concentrate cells, cell components, proteins, DNA or RNA. Dynabeads are super-paramagnetic (they have magnetic properties only when in a magnetic field). The uniform monosized beads have a very slow rate of sedimentation, and binding targets such as streptavidin can easily be attached to the surface of Dynabeads and will isolate target molecules with biotin-based tags. Topics covered are streamlining of peptide-protein pull-down and application of the solid-phase technology. Mann and colleagues use Dynabeads coupled with streptavidin to immobilize desthiobiotinylated synthesized peptides used to attract novel protein pull-down experiments. The experiments have demonstrated that magnetic bead technology extensively improved novel peptide-protein pull-down screens. Mann's group also has elucidated phoshoryl group-dependent binding interactions in the EGF receptor pathway. Pep-tide protein interaction screens are an elegant, flexible method to elucidate modification-dependent protein-protein interactions for multifactoral investigations in parallel.