melanocyte-stimulating hormone receptor activity

Definition

Target type: molecularfunction

Combining with melanocyte-stimulating hormone to initiate a change in cell activity. [GOC:jl, PMID:7581459]

Melanocyte-stimulating hormone receptor activity involves the binding of melanocyte-stimulating hormones (MSHs), including α-MSH, β-MSH, and γ-MSH, to their cognate receptors, melanocortin receptors (MCRs). This interaction initiates a signaling cascade that ultimately leads to the production and release of melanin, the pigment responsible for skin, hair, and eye color. The molecular function of this activity can be broken down into several key steps:

1. **Ligand Binding:** MSHs bind to the extracellular domain of MCRs, specifically to the N-terminal region that contains a highly conserved disulfide-linked loop. This binding event triggers a conformational change in the receptor, leading to its activation.

2. **G-Protein Coupling:** Upon activation, MCRs interact with heterotrimeric G proteins, specifically the Gs protein. This coupling activates the G protein, leading to the dissociation of its alpha subunit from the beta and gamma subunits.

3. **Adenylate Cyclase Activation:** The activated Gαs subunit then interacts with and stimulates adenylate cyclase, an enzyme responsible for the conversion of ATP into cyclic adenosine monophosphate (cAMP).

4. **cAMP Signaling Cascade:** Increased cAMP levels activate protein kinase A (PKA), which phosphorylates various downstream signaling proteins, including cAMP response element-binding protein (CREB).

5. **Gene Transcription:** Phosphorylated CREB binds to specific DNA sequences called cAMP response elements (CREs) located in the promoters of target genes. This binding stimulates the transcription of genes involved in melanin biosynthesis, including the genes encoding tyrosinase, tyrosinase-related protein 1 (TRP1), and tyrosinase-related protein 2 (TRP2).

6. **Melanin Production:** The increased expression of these genes leads to enhanced melanin production within melanocytes. This melanin is then transferred to surrounding keratinocytes, contributing to pigmentation.

Overall, melanocyte-stimulating hormone receptor activity plays a crucial role in regulating pigmentation and other physiological processes by triggering a complex signaling cascade that ultimately results in the production and distribution of melanin.'
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Proteins (3)

Compounds (20)