TY - JOUR
T1 - Heparin-binding Growth-associated Molecule Contains Two Heparin-binding β-Sheet Domains That Are Homologous to the Thrombospondin Type I Repeat
AU - Kilpeläinen, Ilkka
AU - Kaksonen, Marko
AU - Kinnunen, Tarja
AU - Avikainen, Hanna
AU - Fath, Melissa
AU - Linhardt, Robert J.
AU - Raulo, Erkki
AU - Rauvala, Heikki
PY - 2000/5/5
Y1 - 2000/5/5
N2 - Heparin-binding growth-associated molecule (HB-GAM) is an extracellular matrix-associated protein implicated in the development and plasticity of neuronal connections of brain. Binding to cell surface heparan sulfate is indispensable for the biological activity of HB-GAM. In the present paper we have studied the structure of recombinant HB-GAM using heteronuclear MR. These studies show that HB-GAM contains two β-sheet domains connected by a flexible linker. Both of these domains contain three antiparallel β-strands. In addition to this domain structure, HB-GAM contains the N- and C-terminal lysine-rich sequences that lack a detectable structure and appear to form random coils. Studies using CD and MR spectroscopy suggest that HB-GAM undergoes a conformational change upon binding to heparin, and that the binding occurs primarily to the β-sheet domains of the protein. Search of sequence data bases shows that the β-sheet domains of HB-GAM are homologous to the thrombospondin type I repeat (TSR). Sequence comparisons show that the β-sheet structures found previously in midline, a protein homologous with HB-GAM, also correspond to the TSR motif. We suggest that the TSR sequence motif found in various extracellular proteins defines a β-sheet structure similar to that found in HB-GAM and midline. In addition to the apparent structural similarity, a similarity in biological functions is suggested by the occurrence of the TSR sequence motif in a wide variety of proteins that mediate cell-to-extracellular matrix and cell-to-cell interactions, in which the TSR domain mediates specific cell surface binding.
AB - Heparin-binding growth-associated molecule (HB-GAM) is an extracellular matrix-associated protein implicated in the development and plasticity of neuronal connections of brain. Binding to cell surface heparan sulfate is indispensable for the biological activity of HB-GAM. In the present paper we have studied the structure of recombinant HB-GAM using heteronuclear MR. These studies show that HB-GAM contains two β-sheet domains connected by a flexible linker. Both of these domains contain three antiparallel β-strands. In addition to this domain structure, HB-GAM contains the N- and C-terminal lysine-rich sequences that lack a detectable structure and appear to form random coils. Studies using CD and MR spectroscopy suggest that HB-GAM undergoes a conformational change upon binding to heparin, and that the binding occurs primarily to the β-sheet domains of the protein. Search of sequence data bases shows that the β-sheet domains of HB-GAM are homologous to the thrombospondin type I repeat (TSR). Sequence comparisons show that the β-sheet structures found previously in midline, a protein homologous with HB-GAM, also correspond to the TSR motif. We suggest that the TSR sequence motif found in various extracellular proteins defines a β-sheet structure similar to that found in HB-GAM and midline. In addition to the apparent structural similarity, a similarity in biological functions is suggested by the occurrence of the TSR sequence motif in a wide variety of proteins that mediate cell-to-extracellular matrix and cell-to-cell interactions, in which the TSR domain mediates specific cell surface binding.
KW - Receptor-Like Protein Tyrosine Phosphatases, Class 5
KW - neoplasms
KW - Heparin-binding growth
UR - http://www.scopus.com/inward/record.url?scp=0040735688&partnerID=8YFLogxK
U2 - 10.1074/jbc.275.18.13564
DO - 10.1074/jbc.275.18.13564
M3 - Article
C2 - 10788472
AN - SCOPUS:0040735688
VL - 275
SP - 13564
EP - 13570
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 18
ER -