PMID- 3136156
OWN - NLM
STAT- MEDLINE
DCOM- 19880916
LR  - 20210210
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 263
IP  - 23
DP  - 1988 Aug 15
TI  - Modification of calmodulin on Lys-75 by carbamoylating nitrosoureas.
PG  - 11284-90
AB  - This paper describes characterization of the reaction of calmodulin with a series 
      of nitrosoureas which are capable of releasing amine-reactive isocyanates of 
      varying hydrophobic character. The site of calcium-dependent carbamoylation on 
      calmodulin by the antineoplastic agent 
      1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (methyl CCNU) was 
      determined to be Lys-75 as demonstrated using [ring-14C]methyl CCNU and sequence 
      analysis of the sole labeled peptide obtained from tryptic digestion of 
      reversed-phase high pressure liquid chromatography (HPLC)-purified radiolabeled 
      calmodulin. CCNU, the 4-desmethylcyclohexyl derivative of methyl CCNU, and its 
      reactive hydrolysis product, cyclohexyl isocyanate, were also determined to 
      modify calmodulin in a similar manner and at the same site, as demonstrated by 
      specific blockade of modification by the calmodulin antagonist calmidazolium. 
      Nitrosoureas which release the less hydrophobic 4-hydroxy- and 
      4-carboxycyclohexyl isocyanates are unable to modify calmodulin at 25-fold higher 
      concentrations than those required for modification with methyl CCNU, CCNU, or 
      cyclohexyl isocyanate. With this monomodified Lys-75 derivative, purified to 
      homogeneity by HPLC, differential effects of modification on the activation of 
      bovine brain 3',5'-cyclic nucleotide phosphodiesterase (phosphodiesterase) and 
      human erythrocyte Ca2+,Mg2+-ATPase were observed. Compared to the amounts of 
      native calmodulin needed, phosphodiesterase required 7-fold higher amounts of 
      this derivative to reach maximal activation, whereas the activation of the ATPase 
      was unaffected. Clearly, different regions of calmodulin are responsible for the 
      activation of phosphodiesterase and the ATPase. We conclude that Lys-75 is not 
      essential for the function of calmodulin but is in a region of the molecule 
      involved in interaction with phosphodiesterase as well as the binding of certain 
      hydrophobic calmodulin antagonists.
FAU - Mann, D M
AU  - Mann DM
AD  - Graduate Center for Toxicology, University of Kentucky, Lexington 40536.
FAU - Vanaman, T C
AU  - Vanaman TC
LA  - eng
GR  - NS-21868/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (Calmodulin)
RN  - 0 (Carbamates)
RN  - 0 (Imidazoles)
RN  - 0 (Nitrosourea Compounds)
RN  - 4R9H38JAWL (calmidazolium)
RN  - 7BRF0Z81KG (Lomustine)
RN  - EC 3.4.21.4 (Trypsin)
RN  - K3Z4F929H6 (Lysine)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Binding Sites
MH  - Calcium/metabolism
MH  - Calmodulin/*metabolism
MH  - Carbamates/*metabolism
MH  - Cattle
MH  - Hydrogen-Ion Concentration
MH  - Imidazoles/pharmacology
MH  - Lomustine/pharmacology
MH  - *Lysine
MH  - Methylation
MH  - Nitrosourea Compounds/*pharmacology
MH  - Trypsin/metabolism
EDAT- 1988/08/15 00:00
MHDA- 1988/08/15 00:01
CRDT- 1988/08/15 00:00
PHST- 1988/08/15 00:00 [pubmed]
PHST- 1988/08/15 00:01 [medline]
PHST- 1988/08/15 00:00 [entrez]
AID - S0021-9258(18)37955-9 [pii]
PST - ppublish
SO  - J Biol Chem. 1988 Aug 15;263(23):11284-90.