Appeal No.2001-1258 Page 5
Application No. 08/413,805
amino acids (the transmembrane and cytoplasmic domains, the signal peptide
and the propeptide have been deleted.” Examiner’s Answer, page 5. The
examiner acknowledges that Bumol’s truncated variant is missing the first 81
amino acids of SEQ ID NO: 2, but asserts that
Bumol et al. makes [sic] clear that the signal peptide and
propeptide (amino acids 1-81) were deleted in the exemplified
embodiment to facilitate production in prokaryotes because
prokaryotes do not efficiently process eukaryotic signal peptides
and the propeptide portion was deleted because it is not found on
the cell surface (extracellularly).
Id.
The examiner cited Johnson and Hussey as showing that those of skill in
the art would have been motivated to express a truncated GA733-2 variant
consisting of the signal peptide and extracellular domain in eukaryotic cells,
specifically insect cells using a baculovirus expression vector. Both Johnson and
Hussey disclose production of soluble variants of cell-membrane proteins using a
baculovirus/insect cell expression system. Johnson discloses production of
soluble myelin-associated glycoprotein (sMAG). The sMAG construct expressed
by Johnson encoded the signal sequence and extracellular domain of MAG but
was deleted for the transmembrane domain and intracellular domain. See
Figure 1. Johnson reported that insect cells transformed with the recombinant
construct expressed “high levels of sMAG” and that the recombinant proteins
were bound by anti-MAG antibodies. See page 292. Hussey discloses
production of soluble CD4. The baculovirus expression vector used by Hussey
was disclosed to “terminate[] just before the transmembrane region.” Figure 1
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