The high molecular weight nerve growth factor complex from Mastomys natalensis differs from the murine nerve growth factor complex

Abstract

Both the male and the female of Mastomys natalensis, an African rat, have high levels of nerve growth factor (NGF) in their submaxillary glands. Mastomys high molecular weight (HMW) NGF was purified by gel filtration and ion-exchange chromatography and was compared with HMW NGF from the male mouse submaxillary gland. Mastomys HMW NGF sediments as a 5S species, does not exhibit esterase activity, and is more difficult to dissociate at acid pH than mouse 7S NGF. The biological activity could be isolated as a purified Mastomys beta NGF protein identical in size and charge with that purified from male mice. The N-terminal amino acid sequence of the first 20 residues was determined and found to differ from that of mouse only at residue 8. Western blotting of Mastomys 5S NGF using antiserum against mouse beta NGF indicates that the beta NGF subunit of Mastomys is very similar to that of the mouse. Southern blots using a mouse kallikrein probe also demonstrate the presence of a large kallikrein family in Mastomys similar to that in mouse, and Northern blots verify transcription of kallikreins in Mastomys submaxillary gland. SDS-PAGE and isoelectric focusing gels reveal a Mastomys subunit that comigrates with mouse alpha subunit. However, neither oligonucleotide probes directed against mouse alpha subunit RNA nor antibodies directed against mouse alpha NGF cross-react strongly with the Mastomys material. This indicates that the second subunit of the Mastomys complex is not very similar to the mouse alpha subunit.

Biochemical Characterization of Recombinant Human Nerve Growth Factor

“…The best-described activity associated with yprotease is the precursor processing of pro-murine NGF resulting in an enzyme-product complexation as part of the 7s NGF complex (Jongstra-Bilen et al, 1989). Such a complex or its potential has been shown only for murine sources (Darling and Fahnestock, 1988;Schwarz et al, 1989), and the in vivo processing status of the human molecule remains unknown. In light of this, we endeavored to demonstrate that regardless of the processing status of natural human NGF, some of the proteolytic modifications described were not crucial to the expression of biological activities of human NGF.…”

Physicochemical Characterization of Recombinant Human Nerve Growth Factor Produced in Insect Cells with a Baculovirus Vector

“…Proteolytic cleavage at the C-terminus of p-NGF may be peculiar to 7s complex formation in the mouse salivary glands. Although p-NGF is typically found associated with high molecular weight complexes, the 7s complex has been unequivocally detected only in mouse saliva and salivary glands (Bowcock et al, 1988;Darling and Fahnestock, 1988;Drinkwater et al, 1988;Schwarz et al, 1989). There is no information concerning the exact size of P-NGF (i.e., 118 versus 120 amino acids) synthesized in the CNS.…”