Rational design of δPKC translocation inhibitor and activator.
(A) Alignment of the primary sequence of rat δPKC and
mouse θPKC V1 domains (Protein Data Bank accession nos. KIRTCD and
NP_032885, respectively); shadowed boxes indicate identity. Location of
β-strands and the α-helix based on δV1 structure analysis (26)
are indicated below the sequence; sequences most different between the
two isozymes are marked above with a color bracket. (B)
The secondary structure of δV1 (26) (Lower) and a
modeled secondary structure of ɛV1 (G.C., D.M.-R., and L.B.,
unpublished work; Upper) are schematically depicted,
according to ref. 32. Numbering of β-strands in δV1 and ɛV1
domains are marked as in A for δV1. The sequence
corresponding to δV1–1, amino acids 8–17 [SFNSYELGSL], δV1–2,
amino acids 35–45 [ALTTDRGKTLV], and ψδRACK, amino acids 74–81
[MRAAEDPM], are marked as in A, in red, yellow, and
green, respectively. The sequence corresponding to the ɛPKC-selective
inhibitor peptide, ɛV1–2, amino acids 14–21 [EAVSLKPT] (12), and
activator peptide, ψɛRACK, amino acids 85–92 [HDAPIGYD] (13),
are marked in red and green, respectively (Upper).
(C) Crystal structure of the δV1 domain (Protein Data
Bank ID no. 1BDY; ref. 26) is depicted with areas marked in colors
corresponding to those in A and B.
(D) Western blot analysis of cytosolic and particulate
fractions from adult rat cardiac myocytes was carried out as described
(13) to demonstrate isozyme-selective effects on δPKC translocation.
Cells were treated with PMA in the presence and absence of δV1–1.
(Left) Autoradiogram of soluble (S) and particulate (P)
fractions probed with anti-δPKC (Upper) and the same
blot probed with anti-ɛPKC antibodies (Lower).
(Right) Mean ± SEM of data from three experiments;
translocation is expressed as the amount of each isozyme in the
particulate fraction over the amount of that isozyme in nontreated
cells. *, P < 0.05; NS, not significant;
n = 3. (E) Same as in
D, except cells were treated with PMA or ψδRACK and
translocation of δPKC and αPKC is shown. **,
P < 0.01. (F) Same as
D, except cells were treated with δV1–1 in the
presence and absence of ψδRACK. **,
P < 0.01.