I have a vector of strings such as:

```
x <- c("gene_biotype \"protein_coding\"; transcript_name \"IGHV3-66-201\"; 
transcript_source \"havana\"; transcript_biotype \"IG_V_gene\"; 
protein_id \"ENSP00000375041\"; protein_version \"2\"; tag 
\"cds_end_NF\"; tag \"mRNA_end_NF\"; tag \"basic\"; 
transcript_support_level \"NA\";",
"gene_id \"ENSG00000211973\"; gene_version \"2\"; transcript_id 
\"ENST00000390633\"; transcript_version \"2\"; exon_number \"1\"; 
gene_name \"IGHV1-69\"; gene_source \"ensembl_havana\"; gene_biotype 
\"IG_V_gene\"; transcript_name \"IGHV1-69-201\"; transcript_source 
\"ensembl_havana\"; transcript_biotype \"IG_V_gene\"; protein_id 
\"ENSP00000375042\"; protein_version \"2\"; tag \"cds_end_NF\"; tag 
\"mRNA_end_NF\"; tag \"basic\"; transcript_support_level \"NA\";",
"gene_id \"ENSG00000211973\"; gene_version \"2\"; transcript_id 
\"ENST00000390633\"; transcript_version \"2\"; exon_number \"2\"; 
gene_name \"IGHV1-69\"; gene_source \"ensembl_havana\"; gene_biotype 
\"protein_coding\";")

```

I need to extract the quoted text (any characters) that follows gene\_biotype. For example:

```
[1] protein_coding\ 
[2] IG_V_gene\
[3] protein_coding\

```

I have tried using str\_extract in the stringr package, but I cannot get the regex to work. 

Any help would be greatly appreciated!