TY - JOUR
T1 - Identification, partial purification, and localization of a neutral sphingomyelinase in rabbit skeletal muscle
T2 - Neutral sphingomyelinase in skeletal muscle
AU - Ghosh, Nupur
AU - Sabbadini, Roger
AU - Chatterjee, Subroto
PY - 1998
Y1 - 1998
N2 - We have investigated the presence of neutral sphingomyelinases present in rabbit skeletal muscle fractions. Neutral sphingomyelinase activity measurements and Immunoblot analysis of various skeletal muscle fractions indicated that most of the neutral sphingomyelinase was associated with the junctional transverse tubules. Activity gel analysis of the detergent solubilized transverse tubule fraction revealed two distinct bands corresponding to molecular weight on the order of approximately 92 and 53 kDa. Moreover, monospecific antibody raised against pure neutral sphingomyelinase recognized both the 53 and the 92 kDa protein. Peptide mapping studies revealed that both neutral sphingomyelinase isoforms were similar. Moreover, both the enzymes catalyzed the hydrolysis of sphingomyelin to phosphocholine and ceramide. Lithium stimulated and Cu2+ inhibited the activity of both of the enzyme isoforms. However, the 53 kDa isoform was insensitive to activation by Mg2+, and thus differed from the 92 kDa isoform of neutral sphingomyelinase. The localization of neutral sphingomyelinase in skeletal muscle transverse tubule membrane is consistent with transverse tubule production of the sphingomyelin-derived second messenger, sphingosine. Since sphingosine has been shown to modulate calcium release from sarcoplasmic reticulum membranes, our work suggests that neutral sphingomyelinase/sphingosine signaling system may be a physiologically relevant regulator of calcium levels in skeletal muscle.
AB - We have investigated the presence of neutral sphingomyelinases present in rabbit skeletal muscle fractions. Neutral sphingomyelinase activity measurements and Immunoblot analysis of various skeletal muscle fractions indicated that most of the neutral sphingomyelinase was associated with the junctional transverse tubules. Activity gel analysis of the detergent solubilized transverse tubule fraction revealed two distinct bands corresponding to molecular weight on the order of approximately 92 and 53 kDa. Moreover, monospecific antibody raised against pure neutral sphingomyelinase recognized both the 53 and the 92 kDa protein. Peptide mapping studies revealed that both neutral sphingomyelinase isoforms were similar. Moreover, both the enzymes catalyzed the hydrolysis of sphingomyelin to phosphocholine and ceramide. Lithium stimulated and Cu2+ inhibited the activity of both of the enzyme isoforms. However, the 53 kDa isoform was insensitive to activation by Mg2+, and thus differed from the 92 kDa isoform of neutral sphingomyelinase. The localization of neutral sphingomyelinase in skeletal muscle transverse tubule membrane is consistent with transverse tubule production of the sphingomyelin-derived second messenger, sphingosine. Since sphingosine has been shown to modulate calcium release from sarcoplasmic reticulum membranes, our work suggests that neutral sphingomyelinase/sphingosine signaling system may be a physiologically relevant regulator of calcium levels in skeletal muscle.
KW - Neutral sphingomyelinase
KW - Skeletal muscle
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U2 - 10.1023/a:1006910200656
DO - 10.1023/a:1006910200656
M3 - Article
C2 - 9879667
AN - SCOPUS:0031792524
SN - 0300-8177
VL - 189
SP - 161
EP - 168
JO - Molecular and Cellular Biochemistry
JF - Molecular and Cellular Biochemistry
IS - 1-2
ER -