Data::Dumper Output:
$VAR1 = {
  'Symbol4' => {
    'H1SY02' => {
      'Homo Sapiens' => {
        'GO:0008565' => 'protein transporter activity',
        'GO:0015031' => 'protein transport',
        'GO:0006810' => 'transport'
      }
    }
  },
  'Symbol3' => {
    'H1SXZ8' => {
      'Homo Sapiens' => {
        'GO:0008324' => 'cation transmembrane transporter activity',
        'GO:0046872' => 'metal ion binding',
        'GO:0006812' => 'cation transport',
        'GO:0030001' => 'metal ion transport',
        'GO:0055085' => 'transmembrane transport'
      }
    }
  },
  'Symbol1' => {
    'H1SXX9' => {
      'Homo Sapiens' => {
        'GO:0015031' => 'protein transport'
      }
    }
  },
  'Symbol5' => {
    'H1SY06' => {
      'Homo Sapiens' => {
        'GO:0005506' => 'iron ion binding',
        'GO:0004129' => 'cytochrome-c oxidase activity'
      }
    }
  },
  'Symbol2' => {
    'H1SXZ5' => {
      'Homo Sapiens' => {
        'GO:0016597' => 'amino acid binding',
        'GO:0015969' => 'guanosine tetraphosphate metabolic process',
        'GO:0016740' => 'transferase activity',
        'GO:0003824' => 'catalytic activity',
        'GO:0016301' => 'kinase activity',
        'GO:0008152' => 'metabolic process',
        'GO:0016310' => 'phosphorylation',
        'GO:0008728' => 'GTP diphosphokinase activity'
      }
    }
  }
};

Data::Dump Output:
{
  Symbol1 => {
               H1SXX9 => { "Homo Sapiens" => { "GO:0015031" => "protein transport" } },
             },
  Symbol2 => {
               H1SXZ5 => {
                 "Homo Sapiens" => {
                   "GO:0003824" => "catalytic activity",
                   "GO:0008152" => "metabolic process",
                   "GO:0008728" => "GTP diphosphokinase activity",
                   "GO:0015969" => "guanosine tetraphosphate metabolic process",
                   "GO:0016301" => "kinase activity",
                   "GO:0016310" => "phosphorylation",
                   "GO:0016597" => "amino acid binding",
                   "GO:0016740" => "transferase activity",
                 },
               },
             },
  Symbol3 => {
               H1SXZ8 => {
                 "Homo Sapiens" => {
                   "GO:0006812" => "cation transport",
                   "GO:0008324" => "cation transmembrane transporter activity",
                   "GO:0030001" => "metal ion transport",
                   "GO:0046872" => "metal ion binding",
                   "GO:0055085" => "transmembrane transport",
                 },
               },
             },
  Symbol4 => {
               H1SY02 => {
                 "Homo Sapiens" => {
                   "GO:0006810" => "transport",
                   "GO:0008565" => "protein transporter activity",
                   "GO:0015031" => "protein transport",
                 },
               },
             },
  Symbol5 => {
               H1SY06 => {
                 "Homo Sapiens" => {
                   "GO:0004129" => "cytochrome-c oxidase activity",
                   "GO:0005506" => "iron ion binding",
                 },
               },
             },
}