Rabies virus (RABV) is the causative agent of rabies, a severe neurological disease with a 100% fatality rate for symptomatic infection with no therapeutic options. After invading a cell, the rabies virus interacts extensively with host proteins to replicate within the host and circumvent antiviral defense mechanisms. As the RNA of this virus only encodes five proteins, many of the host-viral interactions are mediated by the multifunctional phosphoprotein (P-protein). The functional diversity of P-protein is in part due to discrete functions of the individual domains (two regions of intrinsic disorder separated by a dimerization domain and an ordered C-terminal domain) but also through the expression of the five P-protein isoforms (P1-P5), that differ through N-terminal truncations. These isoforms have distinct phenotypes whereby they show differing organelle localization and interact with different cellular components. The cytosolic P1 is important for viral replication as a cofactor for the RNA polymerase (L protein) and a chaperon of the viral RNA binding N protein. P1 is also a known factor for binding and inhibiting the antiviral transcription factor, STAT1. P3, however, lacks the regions for binding L and N protein, and has gained new functions absent in P1, including microtubule association and bundling, accumulation in the nucleolus. We have also found that P3 binds RNA, whereas P1 does not. Both P1 and P3 have been shown to undergo liquid-liquid phase separation (LLPS), however it is unclear how this property impacts RNA binding. Here we have used crosslinking mass spectrometry method to characterize the structure of P1 and P3 by mapping the proximity between the domains of P-protein P1, P3 as well as P3 mutants P3-D289N and P3-K214A/R260A (called P3-KRm). We have measured abundances of individual crosslinks to determine conformational differences of the four proteins and uncover the structural and functional differences of P1 and P3.