Prediction of the three‐dimensional structures of the nerve growth factor and epidermal growth factor binding proteins (kallikreins) and an hypothetical structure of the high molecular weight complex of epidermal growth factor with its binding protein

Abstract

We have predicted the three‐dimensional structures of the serine protease subunits (γ‐NGF, α‐NGF, and EGF‐BP) of the high molecular weight complexes of nerve growth factor (7S NGF) and epidermal growth factor (HMW‐EGF) from the mouse submandibular gland (from the X‐ray crystal structures of two related glandular kallikreins). The conformations of three of the six loops surrounding the active site are relatively well defined in the models of γ‐NGF and EGF‐BP, but three other loops are likely to have flexible conformations. Although the amino acid sequence of α‐NGF is closely related to those of γ‐NGF and EGF‐BP, it is catalytically inactive. Model‐building studies on α‐NGF suggested that mutations (in α‐NGF) just prior to the active site serine (195) and an unusual N‐terminal sequence are consistent with α‐NGF having a zymogen‐like conformation (similar to that in chymotrypsinogen). An hypothetical model of the quaternary structure of HMW‐EGF has been constructed using this model of EGF‐BP and the NMR structure of murine EGF. The C‐terminal arm of EGF was modeled into the active site of EGF‐BP based on data indicating that the C‐terminal arginine of EGF occupies the S1 subsite of EGF‐BP. Data suggesting one of the surface loops of EGF‐BP is buried in the HMW‐EGF complex and symmetry constraints were important in deriving a schematic model. A molecular docking program was used to fit EGF to EGF‐BP.

To investigate the role of the nervous system of bone in steroid-induced osteonecrosis in rabbits

“…NGF was discovered by Levi-Montalcini and coworkers more than 50 years ago, and belongs to the neurotrophin family, which plays a crucial role in development, maintenance and regeneration of neurons [29]. NGF is part of a high molecular weight peptide, 7S-NGF, which is a complex of 130-140 kDa composed of α, β and γ subunits [68][69][70][71]. In the normal state, NGF is a target-derived neurotrophic molecule and activates two types of receptors, the tropomyosin receptor kinase A (TrkA) receptor and the p75 NTR receptor which belongs to the death receptor family.…”

Synthetic chimeras of mouse growth factor‐associated glandular kallikreins. II. Growth factor binding properties

“…The amino terminal residues are in green, the middle segment residues are in blue, and the carboxyl terminal residues are in red. The atomic coordinates are derived from comparative molecular modeling of porcine pancreatic kallikrein (Bode et al, 1983; see also Bax et al, 1993). Positions A82-A84 are not shown due to their absence in porcine pancreatic kallikrein.…”

“…The individual amino acids involved in these contacts are presently being identified by site-directed mutagenesis. A more detailed model of EGF-BP and its interactions with EGF is described in the accompanying paper (Bax et al, 1993).…”

Synthetic chimeras of mouse growth factor‐associated glandular kallikreins. I. Kinetic properties

“…Thus, the unique kinetic characteristics for EGF-BP and y-NGF have been localized in each case to a few specific amino acid residue positions. Residues associated with growth factor interactions and hypothetical models for the kallikreins and the high molecular weight EGF complex are described in the accompanying reports (Bax et al, 1993;Blaber et al, 1993).…”