Appeal No.2001-1258 Page 8
Application No. 08/413,805
However, the examiner also relies on Johnson and Hussey. These
references disclose production of soluble variants of other membrane proteins in
insect cells, using baculovirus vectors. Johnson and Hussey show, as the
examiner correctly points out, that soluble variants of membrane proteins need
only be deleted for the transmembrane and cytoplasmic domains in order to be
expressed efficiently by insect cells. We also note, although the examiner did not
rely on it, that the instant specification admits that “[t]he baculovirus-insect cell
expression system has been well recognized for its ability to abundantly express
recombinant proteins which most often resemble native protein with respect to
function, immunoreactivity, and immunogenicity.” Page 5.
Thus, we agree with the examiner that it would have been obvious to a
person of ordinary skill in the art, in view of the cited references, to express a
soluble variant of GA733-2 in an insect cell/baculovirus expression system,
because that system was well-known to efficiently produce recombinant proteins.
We also agree that it would have been obvious to express the GA733-2 soluble
derivative consisting of SEQ ID NO: 2, because that amino acid sequence
corresponds to exactly the amino acids disclosed by Szala to make up the signal
sequence and entire extracellular domain of GA733-2. While Bumol’s soluble
GA733-2 derivative was also deleted for the signal sequence and propeptide,
Bumol expressly states that those regions were deleted in order to express the
polypeptide in prokaryotic cells, whereas Johnson and Hussey show that those
regions need not be deleted in order to produce the polypeptide in insect cells.
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