Identification and cloning of the cDNA of a Rb-associated protein RAP140a

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• Retinoblastoma (Rb) protein plays crucial roles in cell-cycle control, gene expression, differentiation, apoptosis, development, and tumorigenesis.
• Rb exerts its functions through interactions with numerous cellular proteins.

Purpose of the Study:

• To identify novel proteins that interact with the Retinoblastoma (Rb) protein.
• To characterize a newly identified cDNA fragment and its corresponding protein.

Main Methods:

• Yeast two-hybrid screening of a human fetal brain cDNA library using partial human Rb as bait.
• Northern blot analysis to detect transcript sizes and distribution.
• Polymerase Chain Reaction (PCR) amplification to clone the full-length cDNA.
• Bioinformatic analysis for protein prediction and chromosomal mapping.

Main Results:

• Six novel cDNA fragments were identified through yeast two-hybrid screening.
• One fragment corresponded to two transcripts (7 kb and 9 kb) ubiquitously distributed in human tissues.
• The full-length cDNA of the 7.2 kb transcript was cloned and named RAP140a, predicted to encode a 1,233 amino acid hydrophilic protein.
• RAP140a was mapped to chromosome 3p13-p14.1.

Conclusions:

• RAP140a is a novel protein identified through its interaction with Rb.
• The distinct transcripts and ubiquitous expression suggest important physiological roles for RAP140a.
• RAP140a may be involved in the intracellular translocation of Rb or other proteins, potentially impacting cellular processes.