2254
These results are the first to demonstrate the structural organization of a vertebrate gene encoding an integral membrane protein of the nuclear envelope that may be a member of a family of polypeptides conserved in evolution .
 integral membrane protein, membrane protein, vertebrate gene
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 integral membrane protein, membrane protein, vertebrate gene