It might be that the fields are TAB separated but I see no evidence for that in the page source, just multiple SPACE characters. If that reflects reality then this code might do the trick.

johngg@shiraz:~/perl/Monks$ perl -Mstrict -Mwarnings -E '
open my $inFH, q{<}, \ <<__EOD__ or die $!;
ProteinName    MF1    MF2    MF3
GH1    Growth factor activity    Growth hormone receptor binding    Ho
+rmone activity
POMC    G protein-coupled receptor binding    Hormone activity    Sign
+aling receptor binding
THRAP3    ATP binding Source    Nuclear receptor transcription coactiv
+ator activity    Phosphoprotein binding 
__EOD__

chomp( my @lines = grep { ! m{^ProteinName} } <$inFH> );
close $inFH or die $!;

say join q{; }, split m{\s{2,}} for @lines;'
GH1; Growth factor activity; Growth hormone receptor binding; Hormone 
+activity
POMC; G protein-coupled receptor binding; Hormone activity; Signaling 
+receptor binding
THRAP3; ATP binding Source; Nuclear receptor transcription coactivator
+ activity; Phosphoprotein binding
[download]

I hope this is helpful.

Update: I should have looked at the download link, they are TABs, so changing m{\s{2,}} to m{\t} would work.