LIMITED POWER OF ATTORNEY

       The undersigned hereby constitutes and appoints each of
Keith Gottesdiener, Carman Alenson and Karen Brown of Prime Medicine,
Inc., a Delaware corporation (the "Company"), and each of Kingsley
Taft and Marishka DeToy of Goodwin Procter LLP, signing singly, and
with full power of substitution, the undersigned's true and lawful
attorney-in-fact to:

	(1)	execute for and on behalf of the undersigned, in
the undersigned's capacity as an officer and/or director of the
Company, from time to time the following U.S. Securities and
Exchange Commission ("SEC") forms: (i) Form ID, including any
attached documents (such as Update Passphrase Authentication), to
effect the assignment of codes to the undersigned to be used in
the transmission of information to the SEC using the EDGAR System;
(ii) Form 3, Initial Statement of Beneficial Ownership of
Securities, including any attached documents; (iii) Form 4,
Statement of Changes in Beneficial Ownership of Securities,
including any attached documents; (iv) Form 5, Annual Statement
of Beneficial Ownership of Securities in accordance with
Section 16(a) of the Securities Exchange Act of 1934, as
amended, and the rules thereunder, including any attached
documents; (v) Schedules 13D and 13G; and (vi) amendments of
each thereof, in accordance with the Securities Exchange Act
of 1934, as amended, and the rules thereunder, including any
attached documents;

	(2)	do and perform any and all acts for and on
behalf of the undersigned that may be necessary or desirable
to complete and execute any such Form 3, 4 or 5, Schedule 13D
or 13G, or any amendment(s) thereto and timely file such
form(s) with the SEC and any securities exchange, national
association or similar authority; and

	(3)	take any other action of any type whatsoever in
connection with the foregoing that, in the opinion of such
attorney-in-fact, may be of benefit to, in the best interest
of, or legally required by, the undersigned, it being understood
that the documents executed by such attorney-in-fact on behalf
of the undersigned pursuant to this Power of Attorney shall be
in such form and shall contain such terms and conditions as such
attorney-in-fact may approve in such attorney-in-fact's discretion.

	The undersigned hereby grants to each such
attorney-in-fact, acting singly, full power and authority to do
and perform any and every act and thing whatsoever requisite,
necessary or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes
as the undersigned might or could do if personally present, with
full power of substitution or revocation, hereby ratifying and
confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do
or cause to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned acknowledges
that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to
comply with Section 16 or Regulation 13D-G of the Securities
Exchange Act of 1934, as amended.  The undersigned hereby agrees
to indemnify the attorneys-in-fact and the Company from and
against any demand, damage, loss, cost or expense arising from
any false or misleading information provided by the undersigned
to the attorneys-in-fact.

	This Power of Attorney shall remain in full force and
effect until the undersigned is no longer required to file
such forms with respect to the undersigned's holdings of and
transactions in securities issued by the Company, unless earlier
revoked by the undersigned in a signed writing delivered to
the foregoing attorneys-in-fact.  This Power of Attorney
supersedes any prior power of attorney in connection with the
undersigned's capacity as an officer and/or director of the
Company.  This Power of Attorney shall expire as to any individual
attorney-in-fact if such attorney-in-fact ceases to be an employee
of the Company or Goodwin Procter LLP, as the case may be.

	IN WITNESS WHEREOF, the undersigned has caused this Power
of Attorney to be executed as of January 17, 2024.

					/s/ Allan Reine
					Signature


					Allan Reine
					Print Name