Microtubule inner protein (MIP) part of the dynein-decorated doublet microtubules (DMTs) in cilia axoneme, which is required for motile cilia beating (By similarity). Suppresses cell death induced by accumulation of unfolded Pael receptor (Pael-R, a substrate of Parkin). Facilitates the formation of inclusions consisting of Pael-R, molecular chaperones, protein degradation molecules and itself when proteasome is inhibited. May play an important role in the formation of Lewy bodies and protection of dopaminergic neurons against Parkinson disease (By similarity). Forms a large molecular chaperone complex containing heat shock proteins 70 and 90 and chaperonin components. Interacts with STIP1, PRKN, GPR37, HSPA8, TCP1/CCT1, CCT2, CCT3, CCT4, CCT5, CCT6A, CCT7 and CCT8 (By similarity). Interacts with MEIG1.