Antiproliferative Factor-Induced Changes in Phosphorylation and Palmitoylation of Cytoskeleton-Associated Protein-4 Regulate Its Nuclear Translocation and DNA Binding

Table 1

Mutant constructs used to study CKAP4 phosphorylation and palmitoylation. CKAP4 mutants that mimic constitutive depalmitoylation and various states of serine (S3, S17 and S19) phosphorylation were generated to determine their effect on the subcellular distribution of CKAP4 in response to APF. CKAP4SΔE translocated from the PM to the nucleus in response to APF; CKAP4SΔA localized to the PM but did not translocate to the nucleus in response to APF; none of the C100S mutants were expressed on the PM; CKAP4C100S/SΔE was expressed in the nucleus. The results indicate that CKAP4 must be palmitoylated for PM expression and depalmitoylated and phosphorylated for translocation to the nucleus. A summary of these results are provided in the table.

Name	Mutations	Comments posttranslational modifications	Resting distribution	Distribution after APF
wild-type (WT) CKAP4	none	expressed or endogenous	PM, ER	> nucleus
CKAP4 C100S	C100S	constitutively depalmitoylated	ER	= ER
CKAP4 SΔA	S3A, S17A, S19A	constitutively dephosphorylated	PM, ER	= PM, ER
CKAP4 C100S/SΔA	C100S, S3A, S17A, S19A	constitutively depalmitoylated, constitutively dephosphorylated	ER	ER
CKAP4 SΔE	S3E, S17E, S19E	mimics phosphorylation	PM, ER	> nucleus
CKAP4 C100S/SΔE	C100S, S3E, S17E, S19E	constitutively depalmitoylated, mimics phosphorylation	Nucleus	= nucleus