Table 1. Analysis of the peptide substrates identified from the IMAP substrate finder assay.

Peptide	Sequence	Amino acid at −1 position	Amino acid at 0 position	Amino acid at +1 position	ΔmP signal
Generic Sequence	GGGRSPGRRRRK	Arginine	Serine	Proline	310
Histone H1 derived	GGGPATPKKAKKL	Alanine	Threonine	Proline	295
Histone H1 derived (aa 9–18)	PKTPKKAKKL	Lysine	Threonine	Proline	280
DYRKtide	RRRFRPASPLRGPPK	Alanine	Serine	Proline	190
CDK7 derived	FLAKSFGSPNRAYKK	Glycine	Serine	Proline	180

The five peptides identified as substrates for CRK3:CYC6 were analysed by sequence alignment. The consensus sequence pattern follows the optimal recognition motif identified for mammalian CDKs.

Sequence pattern: x S/T P x R/K.

Optimal recognition motif for CDKs: x−1 (S/T0) P+1 x+2 (K/R+3).

Underlined are the serine/threonine amino acid residues (in the 0 position) which are phosphorylated by the CRK3:CYC6 protein kinase complex.