Related Experiment Videos
Nucleotide sequence of a growth-related mRNA encoding a member of the prolactin-growth hormone family
Abstract:
As part of the proliferative response to serum, mouse 3T3 cells produce a set of growth-related mRNAs identified by hybridization to cloned cDNAs. One of these mRNAs, which is about 1 kilobase long, appears within a few hours after stimulation of resting cells with serum or platelet-derived growth factor and reaches a high level during the transition from the G1 to the S phase of growth. This mRNA is translated in vitro into a protein of approximately 25 kilodaltons. The corresponding cloned cDNA of 791 base pairs has been sequenced; it contains a single open reading frame that encodes a protein of 224 amino acids with extensive sequence homology to mammalian prolactins. The initial 29-amino acid segment of the encoded protein resembles the signal sequences of prehormones. That the growth-related protein is not mouse prolactin is indicated by comparison of its predicted amino acid composition with that of mouse prolactin and by the distinct fragment patterns seen when restricted mouse DNA is probed with the cloned cDNA or rat prolactin cDNA. Therefore, the growth-related protein appears to be a new member of the prolactin-growth hormone family. Because of its relationship to prolactin and growth hormone and its association with cell proliferation, the protein has been called "proliferin."
Insights
Researchers discovered a new protein, proliferin, involved in cell growth. This protein is related to prolactin and growth hormone, playing a role in the cell cycle.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Mouse 3T3 cells exhibit a proliferative response to serum stimulation.
- Growth-related messenger RNAs (mRNAs) are produced during this response.
- One specific mRNA, approximately 1 kilobase, is upregulated during the G1 to S phase transition.
Purpose of the Study:
- To identify and characterize a novel growth-related protein.
- To investigate the function and classification of this protein.
- To understand its role in cell proliferation.
Main Methods:
- Hybridization of mouse 3T3 cell mRNAs with cloned complementary DNAs (cDNAs).
- In vitro translation of the identified mRNA.
- DNA sequencing of the corresponding cDNA.
- Comparative analysis of predicted amino acid sequences and DNA fragment patterns.
Main Results:
- A 1 kilobase mRNA translates to a 25 kilodalton protein.
- The cDNA sequence reveals homology to mammalian prolactins, with a potential signal sequence.
- Distinctions from mouse prolactin were confirmed through amino acid composition and DNA probing.
Conclusions:
- A novel protein, named "proliferin," has been identified.
- Proliferin is a new member of the prolactin-growth hormone family.
- This protein is associated with cell proliferation and growth factor signaling.