Table 1. Putative Cyt f-interacting proteins which were screened by Y2H in Fig. 7.

No.	Arabidopsis gene locus	Protein	Function in PCD
C-4	NM_118938	P-loop containing nucleoside triphosphate hydrolases	R-protein, the key components of plant immune system, and animal apoptosis regulators CED4/Apaf-1, are P-loop NTPase members32,33
C-9	AY230842	26S proteasome subunit RPN9b	Deletion of RPN9b led to PCD in tobacco26
C-24/25	NM_111928	RING-H2 finger protein ATL72	E3-ubiquitin ligase activity is needed to suppress plant PCD27
C-27	NM_001036850	Nuclear factor Y subunit B13 (NF-YB13)	NF-YB was imported into nucleus to form an intact NF-Y complex, and the latter could induce the expression of anti-apoptotic genes30,31
C-32	NM_121950	Calcium-dependent protein kinase 32 (CDPK32)	CDPK1 interacted with Rpn3 in 26S proteasome, silence of CDPK1 led to premature cell death29