<Table> <Tr> <Td_colspan="3"> hemoglobin (heterotetramer, (αβ)) </Td> </Tr> <Tr> <Td_colspan="3"> </Td> </Tr> <Tr> <Td_colspan="3"> </Td> </Tr> <Tr> <Td_colspan="3"> </Td> </Tr> <Tr> <Td_colspan="2"> Protein type </Td> <Td> metalloprotein, globulin </Td> </Tr> <Tr> <Td_colspan="2"> Function </Td> <Td> oxygen - transport </Td> </Tr> <Tr> <Td_colspan="2"> Cofactor (s) </Td> <Td> heme (4) </Td> </Tr> <Tr> <Td_colspan="3"> </Td> </Tr> <Tr> <Td> Subunit name </Td> <Td> Gene </Td> <Td> Chromosomal locus </Td> </Tr> <Tr> <Td> Hb - α1 </Td> <Td> HBA1 </Td> <Td> Chr. 16 p13. 3 </Td> </Tr> <Tr> <Td> Hb - α2 </Td> <Td> HBA2 </Td> <Td> Chr. 16 p13. 3 </Td> </Tr> <Tr> <Td> Hb - β </Td> <Td> HBB </Td> <Td> Chr. 11 p15. 5 </Td> </Tr> </Table> <Tr> <Td_colspan="3"> hemoglobin (heterotetramer, (αβ)) </Td> </Tr>

Where does oxygen bind in a hemoglobin molecule