Regulatory subunit (beta subunit) of the cytosolic type I platelet-activating factor (PAF) acetylhydrolase (PAF-AH (I)), an enzyme that catalyzes the hydrolyze of the acetyl group at the sn-2 position of PAF and its analogs and participates in PAF inactivation. Regulates the PAF-AH (I) activity in a catalytic dimer composition-dependent manner (By similarity). Positively regulates the activity of the minus-end directed microtubule motor protein dynein. May enhance dynein-mediated microtubule sliding by targeting dynein to the microtubule plus end. Required for several dynein- and microtubule-dependent processes such as the maintenance of Golgi integrity, the peripheral transport of microtubule fragments and the coupling of the nucleus and centrosome. May be required for proliferation of neuronal precursors and neuronal migration. Can self-associate. Component of the cytosolic PAF-AH (I) heterotetrameric enzyme, which is composed of PAFAH1B1 (beta), PAFAH1B2 (alpha2) and PAFAH1B3 (alpha1) subunits. The catalytic activity of the enzyme resides in the alpha1 (PAFAH1B3) and alpha2 (PAFAH1B2) subunits, whereas the beta subunit (PAFAH1B1) has regulatory activity. Trimer formation is not essential for the catalytic activity (By similarity). Interacts with dynein, dynactin, NDE1 and NDEL1. Localizes to the plus end of microtubules and to the centrosome. Expressed in the intermediate and lateral mesoderm, posterior neural tube, notochord and somites of stage 9 embryos. Expressed in the neural tube, roof plate, notochord, somites, dermomymotomes and eye of stage 20 embryos. This expression pattern persists in stage 27 embryos, where expression is also seen in the heart, intestine and dorsal aorta. Weakly and uniformly expressed in the stage 35 embryo. Dimerization mediated by the LisH domain may be required to activate dynein. Belongs to the WD repeat LIS1/nudF family.