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. 2012 Feb 15;7(2):e32120. doi: 10.1371/journal.pone.0032120

Figure 1. Assessing ZMPSTE24-mediated cleavage of the tail from prelamin A in cells blocked at different steps of CAAX processing.

Figure 1

A) Schematic of the post-translational processing pathway for lamin A. Lamin A is synthesized as a precursor, prelamin A, and undergoes CAAX processing (farnesylation, AAX'ing, and carboxylmethylation; steps 1–3), followed by ZMPSTE24-mediated cleavage of the farnesylated, carboxylmethylated tail (step 4). B) An NIH 3T3 stable cell line expressing GFP-lamin A was treated with and without farnesyltransferase inhibitor (FTI). Lysates from these cells were compared to lysates prepared from NIH 3T3 stable cell line expressing GFP-lamin A with a mutation of the CAAX cysteine to serine (C661S) on an 8% SDS-PAGE gel (step 1 block). Lysates prepared from WT MEFs and MEFs containing knockouts of the indicated genes (Rce1, Icmt, and Zmpste24; S. Young, UCLA) were run on 8% gels and probed with antibodies to detect endogenous lamin A. The forms of lamin A are indicated: M (mature), PLA (prelamin A), and PLA(NF) (prelamin A, non-farnesylated).