The StARD (steroidogenic acute regulatory protein-related lipid transfer (START) domain containing) family of proteins is comprised of fifteen different members. All members contain the characteristic START domain and are believed to play key roles in the metabolism and transport of lipids. The StARD proteins are grouped into six subfamilies based on their START domain sequences. PC-TP (StARD2), StARD7, StARD10 and GPBP (StARD11) constitute one subfamily, namely the STARD2/PCTP group. StARD10, also known as PCTP2, PCTPL, NY-CO-28, CGI-52 or SDCCAG28, is widely expressed and functions in phospholipid transfer, binding to phosphatidylcholine and phosphatidylethanolamine. StARD10 can be found in sperm flagellum, potentially functioning as an enzyme involved in energy metabolism, and its expression is developmentally regulated in testis and mammary glands. StARD10 activity can be inhibited via phosphorylation by casein kinase II.