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Reptilian MPR 300 is also the IGF-IIR: cloning, sequencing and functional characterization of the IGF-II binding
Yadavalli Sivaramakrishna1, Praveen Kumar Amancha, Nadimpalli Siva Kumar
1Protein Biochemistry and Molecular Biology Laboratory, Department of Biochemistry, University of Hyderabad, Central University Post Office, Gachibowli, Hyderabad 500 046, India.
Abstract:
The mammalian cation-independent mannose 6-phosphate/insulin-like growth factor (IGF)-II receptor binds IGF-II with high affinity. Ligands transported by the MPR 300/IGF-IIR include IGF-II and mannose 6-phosphate-modified proteins. By targeting IGF-II to lysosomal degradation, it plays a key role in the maintenance of correct IGF-II levels in the circulation and in target tissues. Although, from our studies we found homologous receptor in calotes but its functional significance was not known. We present here the first report on the calotes MPR 300/IGF-IIR binds IGF-II with K(d) of 12.02 nM; these findings provide new and strong evidence that MPR 300/IGF-IIR in Calotes versicolor binds IGFII with high affinity.
Insights
The mannose 6-phosphate/insulin-like growth factor type 2 receptor (MPR 300/IGF-IIR) in the Indian garden lizard, Calotes versicolor, binds to insulin-like growth factor II (IGF-II) with high affinity. This study confirms the functional significance of this receptor in lizards.
Area of Science:
- Comparative endocrinology
- Receptor biology
- Molecular evolution
Background:
- Mammalian cation-independent mannose 6-phosphate/insulin-like growth factor (IGF)-II receptor (MPR 300/IGF-IIR) binds IGF-II and mannose 6-phosphate-modified proteins.
- This receptor is crucial for regulating circulating IGF-II levels by targeting IGF-II for lysosomal degradation.
Purpose of the Study:
- To investigate the functional significance of a homologous MPR 300/IGF-IIR in Calotes versicolor.
- To determine the binding affinity of Calotes MPR 300/IGF-IIR for IGF-II.
Main Methods:
- Biochemical binding assays were employed to assess the interaction between Calotes MPR 300/IGF-IIR and IGF-II.
- Determination of the dissociation constant (K(d)) to quantify binding affinity.
Main Results:
- The Calotes MPR 300/IGF-IIR was found to bind IGF-II with a high affinity.
- The dissociation constant (K(d)) for the Calotes MPR 300/IGF-IIR and IGF-II interaction was determined to be 12.02 nM.
Conclusions:
- This study provides the first report on the functional characterization of MPR 300/IGF-IIR in Calotes versicolor.
- The high-affinity binding of IGF-II by Calotes MPR 300/IGF-IIR suggests a conserved role for this receptor in regulating IGF-II levels across species.
