Binds specifically to cytosolic chaperonin (c-CPN) and transfers target proteins to it (PubMed:19825635). Binds to nascent polypeptide chain and promotes folding in an environment in which there are many competing pathways for nonnative proteins (PubMed:19825635). Together with other chaperonins, contribute to the regulation of gene expression by modulating the spliceosome function on pre-mRNA splicing post-transcriptionally by acting as a co-chaperone of Hsp90 to control levels of LSM8 (By similarity). Required for the biogenesis of tubulins and for subsequent microtubules (MTs) organization and dynamicity (PubMed:19825635). Necessary for tolerance to NaCl salt stress (PubMed:19825635). Involved in the process leading to microtubules dissociation in response to gibberellic acid (GA) probably due to the DELLA proteins-mediated translocation of the prefoldin co-chaperone complex from the cytoplasm to the nucleus (By similarity). Prevents cold acclimation (e.g. 7 days at 4 degrees Celsius) in a DELLA proteins-dependent manner by promoting nuclear proteasome-mediated HY5 degradation, thus modulating the expression of several genes and reducing anthocyanin biosynthesis, but seems not involved in constitutive freezing tolerance (PubMed:28412546). Heterohexamer of two PFD-alpha type and four PFD-beta type subunits forming prefoldin co-chaperone complex (By similarity). Interacts with PFD6 (PubMed:19004800). Binds to the DELLA protein GAI (PubMed:23583555). Interacts with LSM8, a specific subunit of the LSM2-8 complex, which is a core component of the spliceosome (PubMed:32396196). In the presence of gibberellic acid (GA) and at room temperature, the prefoldin complex stays in the cytoplasm and is functional (PubMed:28412546). But in the absence of GA or in response to cold, the prefoldin complex is localized to the nucleus in the presence of DELLA proteins, which severely compromises alpha/beta-tubulin heterodimer availability, thus affecting microtubules (MTs) organization (PubMed:28412546). This changing subcellular localization follows a daily rhythm coordinated oscillation (By similarity). Accumulates in response to cold. Reduced levels of alpha- and beta-tubulin (PubMed:19825635). Altered development patterns and disturbed microtubules (MTs) organization (PubMed:19825635). Hypersensitivity to high NaCl salt levels (PubMed:19825635). Increased capacity to tolerate freezing temperatures upon acclimation (e.g. 7 days at 4 degrees Celsius) associated with a continuous accumulation of HY5 in cold conditions (PubMed:28412546). Belongs to the prefoldin subunit alpha family.