Expression of two different endogenous galactoside-binding lectins sharing sequence homology

Area of Science:

• Molecular Biology
• Biochemistry
• Cancer Research

Background:

• Endogenous beta-D-galactoside-binding lectins are crucial in cellular processes.
• UV-2237-IP3 fibrosarcoma cells express two lectin polypeptides: L-14.5 (14,500 Da) and L-34 (34,000 Da).
• Previous work involved constructing cDNA libraries and isolating lectin cDNA clones.

Purpose of the Study:

• To compare the structure and gene number of lectins in fibrosarcoma cells and normal mouse lung DNA.
• To investigate the differential expression of lectin mRNAs in normal versus transformed cells.
• To determine the nucleotide and amino acid sequences of the lectin cDNA clones.

Main Methods:

• Construction of complementary DNA (cDNA) libraries in lambda gt11.
• Hybridization analysis of messenger RNA (mRNA) expression.
• Nucleotide sequencing of cDNA clones.

Main Results:

• Genomic DNA structure and gene number were similar between fibrosarcoma and normal lung cells.
• mRNA for the Mr 34,000 lectin was more abundant in transformed cells.
• No significant difference in mRNA levels for the Mr 14,500 lectin was observed between cell types.
• The L-14.5 lectin cDNA sequence showed homology to other vertebrate galactoside-binding lectins.
• The Mr 34,000 lectin cDNA sequence shared a conserved 39-amino acid domain with L-14 lectins.

Conclusions:

• The conserved domain suggests a common ancestral gene for L-14 galactoside-binding lectins.
• This domain is likely essential for sugar-binding properties.
• Differential expression of the Mr 34,000 lectin mRNA may play a role in fibrosarcoma development.