Table I. Priming phosphorylation sites in the PKC superfamily.

PKC isotypes	Activation loop	Effect of no phosphate/Ala mutation	C-terminal autophosphorylation	Effect of no phosphate/Ala mutation	C-terminal hydrophobic	Effect of no phosphate/Ala mutation
Classical
α	T497	inactive	T638	inactivation-sensitive	S657	inactivation-sensitive
	TFCGT		TPPDQ		FSYVN
β1(II)	T500	inactive	T641	inactivea	S660	lower
	TFCGT		TPPDQ		FSFVN	relative Ca2+sensitivity
β2(I)	T500		T642	inactive (insoluble?)	S661
	TFCGT		TPTDK		FSYTN
γ	T514		T655		T674
	TFCGT		TPPDR		FTYVN
Novel
δ	T505	low activity	S643	low activity	S662	low activity
	TFCGT		SFSDK		FSFVN
ɛ	T566		T710	low activity	S729	low activity
	TFCGT		TLVDE		FSYFG
η	T513		T655		S674
	TFCGT		TPIDE		FSYVS
θ	T538		S676		S695
	TFCGT		SFADR		FSFIN
Atypical
ζ	T410	low activity	T560		E579
	TFCGT		TPDDE		FEFIN
ι	T403		T574		E555
	TFCGT		TPDDD		FEYIN

The amino acid number of the sites listed varies by one or two residues between different species. The available information on the effect of a lack of phosphate, or an alanine mutation at the priming phosphorylation site, on the catalytic activity is included. The effects are discussed further in the text.

Residues flanking the T641 site in PKCβ2(I) can still be autophosphorylated, and compensate for the lack of phosphate at this site. When the flanking autophosphorylation sites are also mutated to alanine residues, the lack of phosphate at T641 results in an inactive protein.