TY - JOUR
T1 - Unglycosylated Trk protein does not co-localize nor associate with ganglioside GM1 in stable clone of PC12 cells overexpressing Trk (PCtrk cells)
AU - Mutoh, T.
AU - Hamano, T.
AU - Tokuda, A.
AU - Kuriyama, M.
N1 - Funding Information:
The present work was supported in part by the grant-in-aid on the Priority area from the Ministry of Education, Science, and Culture of Japan to T.M.
PY - 2000
Y1 - 2000
N2 - Our previous studies have shown that acidic glycosphingolipid, ganglioside GM1 (GM1), is an endogenous regulator of high affinity nerve growth factor receptor, Trk, which is an essential factor for the normal development and differentiation of neuronal cells by forming a complex with Trk. GM1 is also known to be a major constituent of caveola or glycosphingolipid-enriched microdomain (GEM) of the plasma membrane. In order to study the effect of the glycosylation of Trk on the formation of GM1-Trk complex and subcellular distribution of this protein, we generated PC12 cells stably overexpressing Trk (PCtrk). Pretreatment of this stable clones with tunicamycin, a potent inhibitor of N-glycosylation, caused the appearance of unglycosylated Trk core protein. These unglycosylated Trk can hardly respond to its ligand, NGF. Sucrose density gradient analysis revealed that unglycosylated Trk core protein was recovered in high density fractions, whereas most of GM1 is present in low density fractions corresponding to caveola or GEM fractions. Moreover, these unglycosylated Trk proteins lose their ability to form a complex with GM1, although GM1 is present in the same high density fractions. These data strongly suggest that spatial segregation of GM1 from the Trk protein by the inhibition of the glycosylation of Trk might be an important molecular mechanism for the unresponsiveness to NGF. Moreover, the binding site of GM1 in the Trk protein might act as an important determinant for the normal trafficking of the Trk protein within the cells.
AB - Our previous studies have shown that acidic glycosphingolipid, ganglioside GM1 (GM1), is an endogenous regulator of high affinity nerve growth factor receptor, Trk, which is an essential factor for the normal development and differentiation of neuronal cells by forming a complex with Trk. GM1 is also known to be a major constituent of caveola or glycosphingolipid-enriched microdomain (GEM) of the plasma membrane. In order to study the effect of the glycosylation of Trk on the formation of GM1-Trk complex and subcellular distribution of this protein, we generated PC12 cells stably overexpressing Trk (PCtrk). Pretreatment of this stable clones with tunicamycin, a potent inhibitor of N-glycosylation, caused the appearance of unglycosylated Trk core protein. These unglycosylated Trk can hardly respond to its ligand, NGF. Sucrose density gradient analysis revealed that unglycosylated Trk core protein was recovered in high density fractions, whereas most of GM1 is present in low density fractions corresponding to caveola or GEM fractions. Moreover, these unglycosylated Trk proteins lose their ability to form a complex with GM1, although GM1 is present in the same high density fractions. These data strongly suggest that spatial segregation of GM1 from the Trk protein by the inhibition of the glycosylation of Trk might be an important molecular mechanism for the unresponsiveness to NGF. Moreover, the binding site of GM1 in the Trk protein might act as an important determinant for the normal trafficking of the Trk protein within the cells.
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U2 - 10.1023/A:1026597408790
DO - 10.1023/A:1026597408790
M3 - Article
C2 - 11201795
AN - SCOPUS:0034530123
SN - 0282-0080
VL - 17
SP - 233
EP - 237
JO - Glycoconjugate Journal
JF - Glycoconjugate Journal
IS - 3-4
ER -