[5][6] It was identified by its homology with GRASP65 and the protein's amino acid sequence was determined by analysis of a molecular clone of its complementary DNA.

[6][7] The C-terminus portion of the molecule is called the SPR domain (serine, proline-rich).

[7] GRASP55 is more closely related to homologues in other species, suggesting that GRASP55 is ancestral to GRASP65.

[7][8] GRASP55 is attached to the membrane in two ways; it is myristylated, which attaches it directly to the lipid bilayer; it is also bound indirectly by binding to golgin-45, which binds to a Rab protein, which itself is lipidated and thus anchored to the membrane.

[7] The structure of the Golgi is disrupted during mitosis, and phosphorylation of the SPR domains of GRASP55 and GRASP65 regulate that disruption,[9][8] GRASP55 may also be involved in forming Golgi ribbons, but the evidence is mixed.