The key difference between prolactin and macroprolactin is that prolactin is a physiologically active protein that is best known for its role in enabling females to produce milk, while macroprolactin is a physiologically inactive protein isoform of prolactin found in a small proportion of people.
Prolactin is also known as lactotropin. It is an active protein that enables females to produce milk. It is secreted from the pituitary in response to eating, mating, estrogen treatment, ovulation, or nursing. On the other hand, macroprolactin is a non-bioactive protein isoform of prolactin. Therefore, prolactin and macroprolactin are two active and inactive protein molecules found in people.
CONTENTS
1. Overview and Key Difference
2. What is Prolactin (Lactotropin)
3. What is Macroprolactin
4. Similarities – Prolactin and Macroprolactin
5. Prolactin vs Macroprolactin in Tabular Form
6. Summary – Prolactin vs Macroprolactin
What is Prolactin?
Prolactin is a protein hormone secreted by the anterior pituitary gland. This hormone promotes lactation in response to the suckling stimulus of hungry young mammals. It can influence over 300 separate processes in various vertebrates, including humans. It is also secreted heavily in pulses in between events like eating, mating, estrogen treatment, ovulation or nursing. Prolactin plays a key role in metabolism, regulation of the immune system, and pancreatic development. This protein was first discovered in 1930 by Oscar Riddle from non-human animals. Its presence was confirmed in humans in 1970 by Henry Friesen. Moreover, prolactin is a peptide hormone encoded by the PRL gene.
Figure 01: Prolactin
In mammals, prolactin is found to be associated with milk production. However, in fish, it is involved in controlling water and salt balance. This protein hormone also acts as a cytokine and is an important regulator of the immune system. It has an important cell cycle-related function as a key growth, differentiating, and anti-apoptotic factor. Furthermore, as a growth factor, prolactin binds to cytokine-like receptors and influences hematopoiesis, angiogenesis, and blood clotting regulation. Several variants and isoforms of this protein are known to exist in fish and humans.
What is Macroprolactin?
Macroprolactin is a physiologically inactive protein isoform of prolactin found in a small proportion of people. This isoform of prolactin is non-bioactive. It is usually composed of a prolactin monomer and an IgG molecule. It has a prolonged clearance rate similar to that of immunoglobulins. Moreover, this isoform is clinically non-reactive, but it interferes with immunological assays used for the detection of prolactin. Therefore, macroprolactin is important as some laboratory assays will detect macroprolactin as prolactin. This leads to a falsely elevated prolactin result in lab tests. Furthermore, this can also lead to misdiagnosis of hyperprolactinaemia in some people, especially those with symptoms such as infertility and menstrual problems. There are certain chemicals, such as polyethylene glycol, that remove macroprolactin from the body.
What are the Similarities Between Prolactin and Macroprolactin?
- Prolactin and macroprolactin are two active and inactive protein molecules found in people.
- They are proteins that are made up of amino acids.
- Both forms are found in females as well as males.
- These forms are present in the adult serum.
- Both forms can be detected through laboratory testing.
What is the Difference Between Prolactin and Macroprolactin?
Prolactin is a physiologically active protein that is best known for its role in enabling females to produce milk, while macroprolactin is a physiologically inactive protein isoform of prolactin found in a small proportion in people. Thus, this is the key difference between prolactin and macroprolactin. Furthermore, the molecular weight of prolactin is 23 kDa while the molecular weight of prolactin is 150 kDa.
The below infographic presents the differences between prolactin and macroprolactin in tabular form for side by side comparison.
Summary – Prolactin vs Macroprolactin
Prolactin and macroprolactin are two active and inactive protein molecules found in people. Prolactin is a physiologically active protein that is best known for its role in enabling females to produce milk, while macroprolactin is a physiologically inactive protein isoform of prolactin found in people. So, this summarizes the difference between prolactin and macroprolactin.
Reference:
1. “Macroprolactin.” An Overview | ScienceDirect Topics.
2. “Prolactin.” You and Your Hormones.
Image Courtesy:
1. “Prolactin regulation” By Procedureready – Own work (CC BY-SA 3.0) via Commons Wikimedia