SUMMARY PARAGRAPH for BET4
Bet4p, the alpha subunit of the type II (RAB-protein) geranylgeranyl transferase (GGTase II) (4, 5) forms the catalytic component (component B) along with Bet2p. Bet2p and Bet4p form a stable heterodimer and Mrs6p, the accessory subunit, presents the substrate to these catalytic subunits. GGTase II (Bet2p, Bet4p, Mrs6p) is required for transport between the endoplasmic reticulum and the Golgi, and its role in that pathway seems to be in geranylgeranylating (prenylating) Ypt1p and Sec4p, small GTP-binding proteins that help mediate vesicular traffic. Blocking of prenylation leads to defects in the membrane attachment of Ypt1 and Sec4p (6, 7, 8).
Note: The genetically-defined MAD2 gene was originally identified as YJL031C (see Li R, et al. (1993) Nature 366(6450):82-4, and erratum in Nature (1994) 371(6496):438). It is now known that MAD2, involved in the mitotic spindle checkpoint, is equivalent to YJL030W, while YJL031C/BET4 encodes the alpha subunit of geranylgeranyltransferase type II.
The type II GGTase is one of three prenyl transferases in yeast, the other two being farnesyl transferase and the type I GGTase (8, 5).
Last updated: 2010-05-18