Motor required for the retrograde transport of Golgi vesicles to the endoplasmic reticulum. Has a microtubule plus end-directed motility. Monomer. Interacts with BICD2. Expressed in all tissues examined, with most abundant expression in heart and skeletal muscle. Phosphorylated on tyrosine residues. The disease is caused by variants affecting the gene represented in this entry. Belongs to the TRAFAC class myosin-kinesin ATPase superfamily. Kinesin family. Unc-104 subfamily.