Rabbit Anti-Rat GRASP55 polyclonal antibody for WB, ICC. Golgi reassembly stacking protein of 55 kDa (also called Golgi reassembly-stacking protein of 55 kDa, GRASP55, or Grs2) is encoded by the gene designated as Gorasp2 in rat & mouse (GORASP2/GRS2/GOLPH6 in human). Golgi stack formation involves two homologous peripheral Golgi proteins, GRASP55 and GRASP65, localized to the medial-trans and cis cisternae, respectively. GRASP55 and GRASP65 stack mammalian Golgi cisternae via a common mechanism of phosphorylation-regulated oligomerization. GRASP55 stacks Golgi membranes by forming oligomers through its N-terminal GRASP domain. This process is regulated by phosphorylation within the C-terminal serine/proline-rich domain. Expression of nonphosphorylatable GRASP55 mutants enhances Golgi stacking in interphase cells and inhibits Golgi disassembly during mitosis. Knockdown of either GRASP55 or GRASP65 by siRNA reduces the number of cisternae per Golgi stack, while simultaneous knockdown of both GRASP proteins leads to disassembly of the entire stack.