TY - JOUR
T1 - Calmodulin binds to the cytoplasmic domain of angiotensin-converting enzyme and regulates its phosphorylation and cleavage secretion
AU - Chattopadhyay, Saurabh
AU - Santhamma, Kizhakkekara R.
AU - Sengupta, Saubhik
AU - McCue, Brian
AU - Kinter, Michael
AU - Sen, Ganes C.
AU - Sen, Indira
PY - 2005/10/7
Y1 - 2005/10/7
N2 - The rate of cleavage secretion of the enzymatically active ectodomain of angiotensin-converting enzyme (ACE) is regulated by tyrosine phosphorylation of the protein and by the phorbol ester, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C. Here, we report that both calmodulin inhibitor (CaMI) and calmodulin kinase inhibitor could also enhance cleavage secretion of ACE. This effect was accompanied by the dissociation of calmodulin from a specific region within the cytoplasmic domain of ACE to which it had been bound. The same domain of ACE was phosphorylated, and both CaMI and PMA caused dephosphorylation of ACE as well. Mass spectrometric and mutational analyses identified Ser730 as the only phosphorylated residue in the cytoplasmic domain of ACE. The Ser730 → Ala mutant of ACE was not phosphorylated, but it still bound calmodulin, and its cleavage secretion was enhanced by both CaMI and PMA. Similarly, when Ser730 was replaced by the phosphoserine mimetic, Asp, cleavage secretion of the resultant mutant remained susceptible to the enhancing effect of CaMI and PMA. These results demonstrate that, although CaMI and PMA can enhance both cleavage secretion of ACE and its dephosphorylation, the two effects are not mutually interdependent.
AB - The rate of cleavage secretion of the enzymatically active ectodomain of angiotensin-converting enzyme (ACE) is regulated by tyrosine phosphorylation of the protein and by the phorbol ester, phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C. Here, we report that both calmodulin inhibitor (CaMI) and calmodulin kinase inhibitor could also enhance cleavage secretion of ACE. This effect was accompanied by the dissociation of calmodulin from a specific region within the cytoplasmic domain of ACE to which it had been bound. The same domain of ACE was phosphorylated, and both CaMI and PMA caused dephosphorylation of ACE as well. Mass spectrometric and mutational analyses identified Ser730 as the only phosphorylated residue in the cytoplasmic domain of ACE. The Ser730 → Ala mutant of ACE was not phosphorylated, but it still bound calmodulin, and its cleavage secretion was enhanced by both CaMI and PMA. Similarly, when Ser730 was replaced by the phosphoserine mimetic, Asp, cleavage secretion of the resultant mutant remained susceptible to the enhancing effect of CaMI and PMA. These results demonstrate that, although CaMI and PMA can enhance both cleavage secretion of ACE and its dephosphorylation, the two effects are not mutually interdependent.
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U2 - 10.1074/jbc.M501718200
DO - 10.1074/jbc.M501718200
M3 - Article
C2 - 16096279
AN - SCOPUS:26644474974
SN - 0021-9258
VL - 280
SP - 33847
EP - 33855
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 40
ER -