text: Cation binding to yolk platelet phosvitin
  In addition to non-heme iron [23], yolk phosvitin also contains Ca2+, Mg2+, Na+ and K+ [11]. Partially relaxed 23Na Fourier transform NMR spectra revealed the existence of at least two major intracellular compartments of NMR-visible Na+ [35]. A large fraction of the Rana oocyte Na+ was NMR-invisible and could be recovered in the yolk platelets [35]. During the first meiotic division there is a net increase in NMR-visible Na+; by completion of the second meiotic division (following fertilization), about 70% of the total Na+ becomes NMR-visible. Thus, phosvitin not only serves as a site for energy storage, but also as a storage site for iron and other ions essential for embryonic development in ponds and streams that contain little dissolved salts and minerals.
  
entities.text: ['yolk platelet']
entities.type: Cell
entities.entity_id: PMC-3248852-sec-15_T1
entities.text: ['yolk']
entities.type: Developing_anatomical_structure
entities.entity_id: PMC-3248852-sec-15_T2
entities.text: ['oocyte']
entities.type: Cell
entities.entity_id: PMC-3248852-sec-15_T3
entities.text: ['yolk platelets']
entities.type: Cell
entities.entity_id: PMC-3248852-sec-15_T4
entities.text: ['embryonic']
entities.type: Developing_anatomical_structure
entities.entity_id: PMC-3248852-sec-15_T5
entities.text: ['intracellular compartments']
entities.type: Cellular_component
entities.entity_id: PMC-3248852-sec-15_T6