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. 2020 May 27;9:F1000 Faculty Rev-450. [Version 1] doi: 10.12688/f1000research.22367.1

Figure 2. Rheb maturation takes place through a series of modifications to the C-terminal CaaX motif.

Figure 2.

Human Rheb is translated as a 184-amino-acid protein. The first 169 amino acids contain the GTPase domain (blue). This is followed by a short linker (green) that is sometimes referred to as the hypervariable region. The last four amino acids fit the consensus for a CaaX motif (cysteine followed by two aliphatic amino acids and with flexibility in the final position). This CaaX motif is subsequently farnesylated on the cysteine followed by trimming of the final three amino acids by the ER-localized Ras converting enzyme 1 (RCE1) and methylation of the newly exposed carboxyl group by isoprenylcysteine carboxyl methyltransferase (ICMT, also at the endoplasmic reticulum). Rheb, Ras homolog enriched in brain.