Zink (intrazellulär): the pathway in the body · Biomarker & Blood Analysis

Zink (intrazellulär) is part of the pathway “Zinc”. This page shows the whole pathway; the station of Zink (intrazellulär) is highlighted.

Where this laboratory value sits: Zinc in food — bound to protein. Zinc is found mainly in meat, cheese, nuts, pulses and cereals. It is not free there but bound to proteins and other molecules. The body has no large store of zinc. Source 4

In brief

Zinc is a trace element found in thousands of proteins. It occupies the active site of enzymes, gives zinc finger proteins their shape, and a tiny free share acts as a signal inside the cell. If little zinc is available, zinc enzymes work more slowly.

The pathway step by step

Each station states what the compound does there. Three signs: ↑ supplies — builds up or makes available · ↓ depletes — inhibits, consumes or withholds · ↕ both, depending on amount. Behind it stands what the statement rests on: established physiology, observed in studies, or contested. The signs do not grade; they name the direction.

1. Zinc in food → Free zinc in the gut Digestive enzymes Digestive enzymes break down the proteins and release zinc. Phytate from cereals and pulses binds free zinc ions in the gut contents and holds on to part of them. What stays bound leaves with the stool. Source 4, 1↑ supplies Only as a free ion can zinc bind to the ZIP4 transporter. Phytate forms poorly soluble complexes with zinc; what stays bound in this way is not available for absorption and leaves with the stool. established physiology Source 4, 1
   ⚖ When the balance tips

   too much — If there is a lot of free zinc in the gut contents, the gut cell absorbs more of it until its transporters are saturated; the rest stays in the gut and is excreted.

   too little — If little free zinc is available, for example because phytate binds much of it, less zinc reaches the ZIP4 transporter, and the gut cell inserts more ZIP4.

   established physiology · Source 1, 4

2. Free zinc in the gut → Into the gut cell ZIP4 The ZIP4 transporter sits on the side of the gut cell facing the gut contents and moves zinc into the cell. When little zinc is on offer, the cell inserts more ZIP4. If zinc builds up in the cell, metallothionein also holds back copper. Source 1↑ supplies ZIP4 is the main route for zinc into the gut cell. The cell adjusts the amount to the supply: if little zinc is in the gut, more ZIP4 sits in the membrane; if a lot is present, ZIP4 is broken down. established physiology Source 1
   ⚖ When the balance tips

   too much — If zinc builds up in the gut cell, it makes more metallothionein. This also binds copper and holds it in the cell; the copper is lost with the shed gut cell instead of reaching the blood.

   too little — If little ZIP4 is active, less zinc enters the gut cell, even if there is enough of it in the gut contents.

   established physiology · Source 7, 1

3. Into the gut cell → Zinc in the blood ZnT1 On the other side of the gut cell, the transporter ZnT1 releases zinc into the blood. There it is passed on mostly bound to albumin. If little zinc is in the blood, less of it reaches the tissues. Source 1, 4↑ supplies In the blood, zinc is almost entirely bound to albumin and other proteins and is carried to the tissues in this form. The share in the blood is only a small fraction of the body's zinc and is exchanged rapidly. established physiology Source 1, 4
   ⚖ When the balance tips

   too much — If zinc in the blood rises, the liver and other tissues absorb more of it, and the pancreas and gut release more zinc into the gut, where it is excreted.

   too little — If little zinc is in the blood, less reaches the tissues. During inflammatory processes, the liver additionally draws zinc from the blood via the ZIP14 transporter.

   established physiology · Source 1

4. Zinc in the blood → Zinc in the cell ZIP transporters Cells bring zinc in via ZIP transporters; ZnT transporters move it into storage compartments or back out. Together, both families keep the amount inside the cell constant. If zinc rises, ZnT transporters move more of it out. Source 1↑ supplies ZIP and ZnT transporters distribute zinc to the cytoplasm, the Golgi apparatus and vesicles. There it is built into newly made enzymes or collected, for example in the storage vesicles for insulin. established physiology Source 1
   ⚖ When the balance tips

   too much — If zinc in the cell rises, ZnT transporters move more of it out or into storage compartments, and the cell withdraws ZIP transporters from the membrane.

   too little — If little zinc is in the cell, more ZIP transporters bring zinc in, and ZnT transporters release less of it.

   established physiology · Source 1

5. Free zinc → Metallothionein MTF-1 When free zinc rises, it binds to the switch MTF-1. This attaches to DNA and triggers the formation of metallothionein — a small protein that binds zinc and releases it again as needed. It thus buffers swings in free zinc. Source 3, 5↕ both, depending on amount Metallothionein buffers free zinc: when there is a surplus it picks up as many as seven zinc ions and releases them again when zinc is needed. It also binds copper and cadmium. established physiology Source 7, 5
   ⚖ When the balance tips

   too much — If a lot of metallothionein has been made, it also binds copper, more tightly than zinc; in the gut cell it holds this copper back, and the copper is lost with the shed cell.

   too little — If little metallothionein is available, the buffer is missing: swings in free zinc pass more strongly to enzymes and signalling pathways. This is described mainly in animal models.

   established physiology · Source 7

6. Free zinc → Zinc enzymes In many enzymes, a zinc ion sits firmly in the active site and holds in position the water molecule that carries out the reaction — for example in carbonic anhydrase or alkaline phosphatase. If little zinc is available, these enzymes work more slowly. Source 2↑ supplies The zinc ion makes the bound water reactive. In this way carbonic anhydrase converts carbon dioxide to bicarbonate, and alkaline phosphatase splits off phosphate groups. established physiology Source 2, 8
   ⚖ When the balance tips

   too much — More zinc does not make the finished enzymes faster, because their active site is already occupied; surplus free zinc attaches to secondary sites of some enzymes and inhibits them.

   too little — If little zinc is available, more enzyme molecules remain without zinc in their active site and do not work; zinc-dependent reactions then run more slowly.

   observed in studies · Source 2, 5

7. Free zinc → Zinc finger proteins In zinc finger proteins, zinc holds a small protein loop in shape. Only then does the loop fit a specific site on the DNA, allowing the cell to read genes there. If little zinc is available, these genes are read less often. Source 2, 5↑ supplies Zinc fingers folded with zinc attach to specific sites on the DNA and switch genes on and off. MTF-1 is itself a zinc finger protein and so responds directly to the cell's zinc supply. established physiology Source 2, 3
   ⚖ When the balance tips

   too much — More zinc does not fold zinc fingers further, because their binding sites are already occupied; the cell intercepts additional zinc via MTF-1 and metallothionein.

   too little — If little zinc is available, some zinc fingers remain unfolded and do not find their site on the DNA; the genes there are read less often.

   observed in studies · Source 6, 3, 5

Further stations

• Zinc in food — bound to protein Zinc is found mainly in meat, cheese, nuts, pulses and cereals. It is not free there but bound to proteins and other molecules. The body has no large store of zinc. Source 4↑ supplies Food is the only source of zinc; there is no large store the body can draw on for long. How much arrives depends on the accompanying substances: zinc is readily released from protein, while phytate holds it back. established physiology Source 4
  ⚖ When the balance tips

  too much — If a lot of zinc arrives, the gut absorbs a smaller share of it; more stays in the gut contents and is excreted.

  too little — If little zinc arrives, the gut absorbs a larger share of it, and less of the body's own zinc is lost via the gut.

  established physiology · Source 1, 4

• Free zinc — a very small amount Almost all zinc in the cell is bound to proteins. Only a tiny, freely mobile fraction remains — and it is exactly this fraction that acts as a signal. In small amounts it slows enzymes such as phosphatases. Source 2, 5↕ both, depending on amount Free zinc acts as a signal: in small amounts it slows enzymes such as phosphatases and thus alters signalling pathways in the cell. If it rises further, it occupies binding sites that belong to other metals or proteins. observed in studies Source 5, 2
  ⚖ When the balance tips

  too much — If free zinc builds up, it attaches to enzymes that do not need it and inhibits them; in cell culture this strains the cell. Via MTF-1 the cell then makes more metallothionein.

  too little — If little free zinc is available, zinc signals become weaker, and enzymes it normally slows stay active longer.

  observed in studies · Source 5, 3

Cofactors in this pathway

• Cysteine — The sulfur of its side chain binds zinc in zinc fingers and in metallothionein; it thus holds zinc firmly bound Source 6, 7
• Histidine — The nitrogen of its side chain binds zinc in many enzymes and zinc fingers; zinc thus stays in place Source 6In the ORY catalogue as a laboratory value: Histidin
• Magnesium — Sits next to two zinc ions in the active site of alkaline phosphatase; together they split off phosphate Source 8In the ORY catalogue as a laboratory value: Magnesium
• Copper — The second metal of superoxide dismutase 1: copper converts, zinc holds the shape; the enzyme breaks down superoxide Source 9In the ORY catalogue as a laboratory value: Kupfer (Cu)

Sources

1. Kambe T, Tsuji T et al. The Physiological, Biochemical, and Molecular Roles of Zinc Transporters in Zinc Homeostasis and Metabolism. Physiol Rev 2015 · PubMed 26084690
2. Maret W. Zinc biochemistry: from a single zinc enzyme to a key element of life. Adv Nutr 2013 · PubMed 23319127
3. Andrews GK. Cellular zinc sensors: MTF-1 regulation of gene expression. Biometals 2001 · PubMed 11831458
4. Stiles LI, Ferrao K et al. Role of zinc in health and disease. Clin Exp Med 2024 · PubMed 38367035
5. Maret W. Zinc in Cellular Regulation: The Nature and Significance of "Zinc Signals". Int J Mol Sci 2017 · PubMed 29088067
6. Maret W. Zinc coordination environments in proteins determine zinc functions. J Trace Elem Med Biol 2005 · PubMed 16240665
7. Coyle P, Philcox JC, Carey LC et al. Metallothionein: the multipurpose protein. Cell Mol Life Sci 2002 · PubMed 12022471
8. Coleman JE. Structure and mechanism of alkaline phosphatase. Annu Rev Biophys Biomol Struct 1992 · PubMed 1525473
9. Leitch JM, Yick PJ, Culotta VC. The right to choose: multiple pathways for activating copper,zinc superoxide dismutase. J Biol Chem 2009 · PubMed 19586921

Whole pathway: Zinc

Related pathways

• Histamine — Histidin, Kupfer (Cu)
• Dopamine, noradrenaline, adrenaline — Magnesium, Kupfer (Cu)

As of 2026-09-16. Draft, written by Claude to schema v2; sources checked in PubMed; expert approval pending
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