Centrosomes are the main microtubule organizing centers in animal cells. Centrosomes consist of a pair of centrioles surrounded by a matrix of pericentriolar material (PCM) that assembles from cytoplasmic components. In C. elegans embryos, interactions between the coiled coil proteins SPD-5, SPD-2, and the kinase PLK-1 are critical for PCM assembly. However, it is not known if these interactions promote the formation of cytoplasmic complexes that are added to the PCM or if components only interact during incorporation into the PCM matrix. Here, we address this problem by using a combination of live-cell fluorescence correlation spectroscopy, mass spectrometry, and hydrodynamic techniques to investigate the native state of PCM components in the cytoplasm. We show that SPD-2 is monomeric and neither SPD-2 nor SPD-5 exist in complex with PLK-1. SPD-5 exists as a monomer but also forms complexes with the PP2A-regulatory proteins RSA-1 and RSA-2, which are required for microtubule organization at centrosomes. These results suggest that the interactions between SPD-2, SPD-5 and PLK-1 do not result in formation cytoplasmic complexes, but instead occur in the context of PCM assembly.