Acts as one of several non-catalytic accessory components of the cytoplasmic dynein 1 complex that are thought to be involved in linking dynein to cargos and to adapter proteins that regulate dynein function. Cytoplasmic dynein 1 acts as a motor for the intracellular retrograde motility of vesicles and organelles along microtubules. Homodimer. The cytoplasmic dynein 1 complex consists of two catalytic heavy chains (HCs) and a number of non-catalytic subunits presented by intermediate chains (ICs), light intermediate chains (LICs) and light chains (LCs); the composition seems to vary in respect to the IC, LIC and LC composition. The heavy chain homodimer serves as a scaffold for the probable homodimeric assembly of the respective non-catalytic subunits. The ICs and LICs bind directly to the HC dimer and the LCs assemble on the IC dimer. Self-associates. Interacts with DYNLRB2. Interacts with DYNC1I1 and DYNC1I2. Interacts with RAB6A isoform 1 (GTP-bound); the interaction is direct. Interacts with RAB6A isoform 2 (GDP-bound); the interaction is direct. Interacts with RAB6B (GDP-bound). Additional isoforms seem to exist. High expression in heart, liver, brain and pancreas; moderate in placenta, skeletal muscle and kidney; low in lung, prostate, testis, small intestine and colon. Isoform 1 expression is up-regulated in 64% hepatocellular carcinoma (HCC) patients. May result from the retention of an intron in the cDNA. Belongs to the GAMAD family.