Component of the TRAPP complex, which is involved in endoplasmic reticulum to Golgi apparatus trafficking at a very early stage (PubMed:21525244, PubMed:28777934). Also plays a role in chromosome congression, kinetochore assembly and stability and controls the recruitment of CENPE to the kinetochores (PubMed:25918224). Component of the multisubunit TRAPP (transport protein particle) complex, which includes at least TRAPPC2, TRAPPC2L, TRAPPC3, TRAPPC3L, TRAPPC4, TRAPPC5, TRAPPC8, TRAPPC9, TRAPPC10, TRAPPC11 and TRAPPC12 (PubMed:21525244). Interacts with CENPE (PubMed:25918224). Mainly localizes to structures resembling the Golgi and a small amount is found in the nucleus. Phosphorylated as the cells enter mitosis but is dephosphorylated at or before the onset of anaphase. The phosphorylated form recruits CENPE to kinetochores more efficiently than the non-phosphorylated form. The disease is caused by variants affecting the gene represented in this entry. Cells display a fragmented Golgi apparatus (PubMed:28777934). Truncated N-terminus.