Previous results from our laboratory assert that the yeast Hsp40 chaperone protein Swa2 is essential for the propagation of the prion [URE3] in a yeast population. Swa2 is the sole yeast homolog of mammalian protein auxilin, which functions in vesicle‐mediated endocytosis by disassembling the structural lattice formed by the protein clathrin. The objective of this study was to find the determinants of the specific genetic interaction between Swa2 and [URE3]. The primary method used in this study was complementation by plasmid‐shuffling in the budding yeast Saccharomyces cerevisiae. Summary of Results: Our investigation revealed that two regions of the Swa2 protein, the J‐domain and the tetratricopeptide repeat region (TPR) are both necessary and sufficient to maintain [URE3], but that the TPR domain is solely responsible for prion/chaperone specificity. While the function of the TPR domain in Swa2 is undetermined, TPR domains typically act as docking platforms for a variety of protein complexes. As such we propose that the Swa2 TPR domain either participates in a bipartite interaction with Hsp70, analogous to the C‐terminal domains of other yeast Hsp40s, or that the TPR domain mediates the formation of a ternary complex with another undetermined protein in [URE3] propagation. We expect that understanding the function of the Swa2 TPR domain will provide new insight into both J‐protein function and the complex mechanisms of prion propagation.This work was supported by a Single‐Investigator Cottrell College Science Award (Award #21010) from the Research Corporation for Science Advancement and by by the National Institute Of General Medical Sciences of the National Institutes of Health under Award Number R15GM110606.