Golgi matrix protein playing a role in tethering of vesicles to Golgi membranes and in maintaining the overall structure of the Golgi apparatus. Functions in the anterograde transport of storage protein precursors from the endoplasmic reticulum (ER) to the Golgi complex. Concentrates only on one side of the Golgi bodies. The C-terminal domain (689-914) is necessary and sufficient for Golgi targeting. Dwarf plants and accumulation of the precursors of the two major storage proteins albumin 2S and globulin 12S in dry seeds.