Unconfigured Ad

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • sbdk82
    Member
    • Jul 2014
    • 26

    command line BLASTP with description

    How can I get the description( first column in the figure) when I run the command line blastp?
    I am using the following options
    Code:
    -outfmt "6 std qlen slen"
    Last edited by sbdk82; 12-08-2018, 04:55 PM.
  • ashishbansal
    Member
    • Dec 2018
    • 17

    #2
    First, we need to tell blast about our database. BLAST needs to do some pre-work on the database file prior to searching. This helps to make the software work a lot faster. Because you installed your own version of the sotware, you need to tell the shell where the software is located. Use the full path and the makeblastdb command:
    makeblastdb -in human.1.protein.faa -dbtype prot
    ls
    Note that this makes a lot of extra files, with the same name as the database plus new extensions (.pin, .psq, etc). To make blast work, these files, called index files, must be in the same directory as the fasta file.
    Now we can run the blast job. We will use blastp, which is appropriate for protein to protein comparisons.
    blastp -query cow.small.faa -db human.1.protein.faa
    This gives us a lot of information on the terminal screen. But this is difficult to save and use later - Blast also gives the option of saving the text to a file.
    blastp -query cow.small.faa -db human.1.protein.faa -out cow_vs_human_blast_results.txt
    ls
    Take a look at the results using less. Note that there can be more than one match between the query and the same subject. These are referred to as high-scoring segment pairs (HSPs).
    less cow_vs_human_blast_results.txt
    So how do you know about all the options, such as the flag to create an output file? Lets also take a look at the help pages. Unfortunately there are no man pages (those are usually reserved for shell commands, but some software authors will provide them as well), but there is a text help output
    blastp -help
    To scroll through slowly
    blastp -help | less
    To quit the less screen, press the q key.
    Parameters of interest include the -evalue (Default is 10?!?) and the -outfmt
    Lets filter for more statistically significant matches with a different output format:
    blastp \
    -query cow.small.faa \
    -db human.1.protein.faa \
    -out cow_vs_human_blast_results.tab \
    -evalue 1e-5 \
    -outfmt 7
    I broke the long single command into many lines with by “escaping” the newline. That forward slash tells the command line “Wait, I’m not done yet!”. So it waits for the next line of the command before executing.
    Clinical Research

    Comment

    Latest Articles

    Collapse

    • SEQadmin2
      Advanced Sequencing Platforms Tackle Neuroscience’s Toughest Genomics Problems
      by SEQadmin2



      Genomics studies in neuroscience face a special challenge due to the brain’s complexity and scarcity of samples. Mapping changes in cell type and state using conventional next-generation sequencing methods remains challenging. Advances in technologies like single-cell sequencing, spatial transcriptomics, and long-read sequencing have opened the door to deeper studies of the brain and diseases like Alzheimer’s, amyotrophic lateral sclerosis (ALS), and schizophrenia.
      ...
      07-09-2026, 11:10 AM
    • SEQadmin2
      Cancer Drug Resistance: The Lingering Barrier to Rising Survival
      by SEQadmin2



      Cancer survival rates have significantly increased in the last few decades in the United States, reaching a combined 70% 5-year survival rate by 2021. Behind this number, there are years of research to find new therapies, drug targets, and early detection methods. But there is one core challenge that keeps slowing down these advances, and it’s about drug resistance.

      There is no single reason why many patients don’t respond to treatment as expected. Cancer is...
      07-08-2026, 05:17 AM
    • GATTACAT
      Reply to Nine Things a Sample Prep Scientist Thinks About Before Sequencing
      by GATTACAT
      Love this - good data definitely starts from good input, and poor input can only give relatively poor data. I particularly like the mention of Nanodrop/absorbance based methods for quantification. It's such a toss up if you'll get an accurate reading or what amounts to a randomly generated number, and a lot of library/sequencing related issues can be traced back to poor quant.
      07-01-2026, 11:43 AM

    ad_right_rmr

    Collapse

    News

    Collapse

    Topics Statistics Last Post
    Started by SEQadmin2, 07-13-2026, 10:26 AM
    0 responses
    26 views
    0 reactions
    Last Post SEQadmin2  
    Started by SEQadmin2, 07-09-2026, 10:04 AM
    0 responses
    35 views
    0 reactions
    Last Post SEQadmin2  
    Started by SEQadmin2, 07-08-2026, 10:08 AM
    0 responses
    22 views
    0 reactions
    Last Post SEQadmin2  
    Started by SEQadmin2, 07-07-2026, 11:05 AM
    0 responses
    34 views
    0 reactions
    Last Post SEQadmin2  
    Working...