Installing SSL with only a .pem file

Is it possible to install SSL certificate in Centos (6.5) and apache with just a .pem file? I have been told by the client that they do not have a .crt file or a .key file. It is a wildcard certificate that I need to install in one of the subdomain.

What is the use of PEM file in SSL?

PEM files are used to store SSL certificates and their associated private keys. Multiple certificates are in the full SSL chain, and they work in this order: The end-user certificate, which is assigned to your domain name by a certificate authority (CA). This is the file you use in nginx and Apache to encrypt HTTPS.

Extensions do not matter. Usually .crt is used for a certificate in PEM format and .key for the matching key. Both are base64 encoded data with a PEM header like "---- BEGIN CERTIFICATE ---" or "----- BEGIN RSA PRIVATE KEY -----". But you can put both certificate and key together in a single PEM file and use this inside the certificate and key parameters. But, of course, you have to make sure that your *.pem files really contains both certificate and key.