On 2014 Oct 23, Toby Gibson commented:

LATS protein kinases function in the Hippo signalling system. They are basophilic kinases known to phosphorylate sites that match Hx[Rk]xx[ST] motifs. The requirement for a His residue marks out LATS from other AGC group basophilic kinases. LATS substrate proteins usually have multiple matches to these motifs, as for example YAP1 (human) and SSD1 (yeast). In these proteins the LATS P-sites are in regions of natively disordered polypeptide.

The LATS substrate reported here, Snail1 does have two matches to the LATS site as shown in Fig. 3

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252572/figure/f3/

But these lie within DNA-binding zinc finger domains. The His residues are part of the zinc coordinating residues that hold the domain in a folded conformation. So long as the zinc fingers are folded, these His sidechains are unavailable to access a kinase active site cleft. Indeed all the residues in the proposed site(s) are in alpha helices when the zinc fingers are folded. The H, R and T residues are conserved in many other zinc finger proteins. If Snail1 zinc fingers can be phosphorylated by LATS then many other zinc finger proteins should also be targets. Because of the restricted focus of the HIPPO signalling pathway and the limited number of known LATS substrates in fly, yeast and mammal systems, this might be unlikely.

In the absence of biophysical data showing that the Snail1 sites can become accessible under plausible phosphorylation conditions, they are considered to be false positive sites in our ELM resource entry for LATS kinases

http://elm.eu.org/elms/elmPages/MOD_LATS_1.html

On 2014 Oct 23, Toby Gibson commented:

LATS protein kinases function in the Hippo signalling system. They are basophilic kinases known to phosphorylate sites that match Hx[Rk]xx[ST] motifs. The requirement for a His residue marks out LATS from other AGC group basophilic kinases. LATS substrate proteins usually have multiple matches to these motifs, as for example YAP1 (human) and SSD1 (yeast). In these proteins the LATS P-sites are in regions of natively disordered polypeptide.

The LATS substrate reported here, Snail1 does have two matches to the LATS site as shown in Fig. 3

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252572/figure/f3/

But these lie within DNA-binding zinc finger domains. The His residues are part of the zinc coordinating residues that hold the domain in a folded conformation. So long as the zinc fingers are folded, these His sidechains are unavailable to access a kinase active site cleft. Indeed all the residues in the proposed site(s) are in alpha helices when the zinc fingers are folded. The H, R and T residues are conserved in many other zinc finger proteins. If Snail1 zinc fingers can be phosphorylated by LATS then many other zinc finger proteins should also be targets. Because of the restricted focus of the HIPPO signalling pathway and the limited number of known LATS substrates in fly, yeast and mammal systems, this might be unlikely.

In the absence of biophysical data showing that the Snail1 sites can become accessible under plausible phosphorylation conditions, they are considered to be false positive sites in our ELM resource entry for LATS kinases

http://elm.eu.org/elms/elmPages/MOD_LATS_1.html